Lexical vs. Structural Meaning: How Words Shape Sentences

Every sentence you speak or write is built on two distinct layers of meaning working in tandem. One layer tells you what is being talked about – the people, places, actions, and qualities at the heart of a message. The other layer tells you how all those pieces relate to each other grammatically. These two layers correspond to two fundamental types of word meaning in linguistics: lexical meaning and structural meaning. Understanding the difference between them is not just academic – it reveals exactly how language constructs sense, and why every word in a sentence, no matter how small, earns its place.

Defining lexical meaning and structural meaning 🔗

At the most basic level, lexical meaning refers to the standalone, dictionary-level content that a word carries. It is the meaning you find when you look a word up – the concept, thing, action, or quality it represents. Words with lexical meaning are called content words, and they are responsible for delivering the core information of a sentence.

Structural meaning, by contrast, is the meaning that comes not from a word’s dictionary definition but from its grammatical role within a sentence. Function words – also called structure words or grammatical words – carry this type of meaning. According to linguist C. C. Fries, who first formally proposed this distinction in 1952, function words signal the relationships that content words have to one another, effectively acting as the glue holding sentences together.

Think of it this way: content words supply the raw material of a message, while structure words determine how that material is organized and what it means in relation to everything else. Remove the content words from a sentence, and you lose the substance. Remove the structure words, and you often lose clarity, precision, and grammatical coherence.

Content words and lexical meaning 🔗

Content words belong to what linguists call open classes – categories that regularly expand as new words enter a language. When English gained words like “podcast,” “selfie,” or “blockchain,” these were all content words. The four primary open-class categories are nouns, verbs, adjectives, and adverbs, and together they carry the bulk of a sentence’s lexical meaning.

Nouns 🔗

Nouns name people, places, things, and ideas. Words like mountain, justice, teacher, and rainfall all carry clear, dictionary-definable meanings. In the sentence “The scientist published her research,” the nouns scientist and research immediately tell you who and what the sentence is about. Their lexical meaning is self-contained – you know what both words mean even in isolation.

Verbs 🔗

Verbs depict actions, events, and states. Words like collapse, whisper, grow, and discover each carry a distinct, lookable-up meaning. In “The bridge collapsed,” the verb collapsed carries powerful lexical content – it tells you precisely what happened. It is worth noting here that not all verbs are content words. Auxiliary verbs like could, have, and be often function as structure words when they are used to form tenses rather than to express a standalone meaning.

Adjectives 🔗

Adjectives modify nouns by adding descriptive detail – color, size, quality, origin, and so on. Fragile, enormous, ancient, and transparent all carry lexical meaning that enriches the nouns they modify. In “She held a fragile vase,” the adjective fragile adds specific lexical information that changes how you picture the object. Without it, the vase is just a vase.

Adverbs 🔗

Adverbs modify verbs, adjectives, or other adverbs, and many of them carry clear lexical meaning. Suddenly, carefully, fiercely, and yesterday all convey specific information about manner, time, place, or degree. In “He spoke quietly,” the adverb quietly provides lexical detail about how the speaking was done. As Grammarly’s grammar guide notes, adverbs give details about actions such as where, when, why, or how often something occurs.

A key feature of all these content-word categories is that their meanings are definable and relatively stable. Encyclopaedia Britannica’s linguistics entry points out that dictionaries are essentially inventories of lexical meaning – structured lists of content words with their associated concepts. You can point to most content words and say with confidence what they refer to.

Structure words and structural meaning 🔗

Structure words belong to closed classes – categories that rarely, if ever, accept new members. English hasn’t gained a new preposition, conjunction, or article in centuries. Function words like “the,” “of,” “in,” “might,” and “whether” are part of a fixed, stable inventory precisely because their job is grammatical rather than descriptive. New concepts demand new content words, but grammar doesn’t need new structure words to accommodate them.

Articles and determiners 🔗

Articles are among the clearest examples of structural meaning at work. Consider the difference between “I saw a dog” and “I saw the dog.” The noun dog carries the same lexical meaning in both sentences. But a signals that the speaker is referring to any unspecified dog, while the signals a specific one – a dog both speaker and listener already have in mind. As the Encyclopedia of Linguistics explains, determiners add grammatical information about specificity and definiteness without altering the core meaning of the noun they accompany.

Prepositions 🔗

Prepositions like of, in, on, between, and through express relational meanings – spatial, temporal, and logical relationships between content words. In “The keys are on the table,” the preposition on establishes the spatial relationship between keys and table. Neither keys nor table changes meaning, but without on, the grammatical relationship between them would be unclear. Prepositions do not carry standalone meaning – say “on” in isolation and it tells you nothing useful – but within a sentence, they do vital relational work.

Auxiliary verbs 🔗

Auxiliary verbs are a particularly instructive case because the same word can function as either a content word or a structure word depending on context. ELT Concourse’s analysis of function words makes this clear: “I have a house” uses have as a content word meaning “to own,” while “I have been gardening” uses have as a structure word that forms a tense. The word is identical; only its grammatical role – and therefore the type of meaning it carries – differs.

Modal auxiliaries like could, might, shall, and must are almost always structure words. They don’t describe a concrete action or thing; instead, they communicate grammatical information about possibility, obligation, or conditionality. “She could leave” and “She will leave” describe the same action – leaving – but the auxiliaries could and will shift the entire grammatical and relational meaning of the sentence.

Conjunctions 🔗

Conjunctions like and, but, although, and because are pure structural connectors. They carry no lexical content of their own, but they determine how clauses and phrases relate to each other. “She studied hard, so she passed” is structurally very different from “She studied hard, but she failed” – the content words are almost identical, but the conjunction completely changes the logical relationship being expressed.

Open class vs. closed class: why the distinction matters 🔗

The open/closed class distinction maps directly onto lexical vs. structural meaning. Open-class (lexical) categories are expandable because language always needs new words to describe new things, concepts, and actions. Closed-class (structural) categories are fixed because the grammatical framework of a language is largely stable – English doesn’t need new prepositions or articles just because new concepts emerge.

This also explains a practical difference in how dictionaries and grammars treat each type. As the Wikipedia entry on function words notes: “Dictionaries define the specific meanings of content words but can describe only the general usages of function words. By contrast, grammars describe the use of function words in detail but treat lexical words only in general terms.” In other words, you look up content words in a dictionary and structure words in a grammar book – each belongs to a different kind of reference precisely because they do different kinds of work.

Why both meanings are essential for effective communication 🔗

One of the best ways to appreciate how dependent these two meaning types are on each other is to strip sentences down to their parts. Consider: “Scientist – publish – research.” The lexical meaning is there. You understand the general situation. But now add structure words: “The scientist published her groundbreaking research.” The sentence becomes specific, temporally located, and grammatically complete. The structural words – the, her, the past tense marking – transform a rough sketch into a precise statement.

The reverse experiment is equally telling. Remove content words and keep only structure: “The – of – could – and.” Nothing is communicated. Structure words without content words produce grammatically shaped emptiness. As the Essentials of Linguistics textbook explains, functional categories can be thought of as the grammatical glue that holds syntax together – but glue without material to bind is useless.

Structure words and the limits of translation 🔗

The difference between lexical and structural meaning also shows up sharply in translation. Most content words translate relatively directly – dog is Hund in German, cane in Italian, chien in French. But structure words are notoriously difficult to translate because their meaning is so tightly bound to the grammatical system of a specific language. As ELT Concourse points out, even something as seemingly simple as “either…or” creates serious translation challenges across languages – some render the concept with a single word, some with two, some with three entirely different constructions.

This reflects a deep truth about structural meaning: it is not universal. The specific grammatical relationships that structure words encode vary from language to language, which is why Britannica’s discussion of language and meaning notes that features like word order, inflection, and grammatical particles – all carriers of structural meaning – differ markedly across languages even when the underlying lexical content is the same.

The continuum between lexical and structural meaning 🔗

It’s important to recognize that lexical and structural meaning don’t always fall into neat, separate boxes. As the EBSCO Research primer on the Lexical Approach explains, words exist on a continuum. At one end are highly specialized content words like “pneumonia” or “electromagnetic,” whose meaning is fully self-contained. At the other end are words like “the,” “of,” and “this,” which get their meaning almost entirely from the words they combine with. Most words fall somewhere in the middle of this continuum, carrying varying degrees of both lexical and structural meaning. Prepositions like “behind” or “through,” for example, carry some spatial lexical content alongside their grammatical relational function.

Understanding this continuum – rather than thinking in rigid either/or terms – gives a more accurate picture of how meaning actually operates in language. Words don’t just switch cleanly between two modes; they participate in a rich, layered system where lexical and structural meaning constantly interact.

Putting it all together: a sentence-level view 🔗

Consider the sentence: “She could hear the distant thunder.” Break it down and both types of meaning become visible. The content words – hear, distant, thunder – provide the lexical core: an act of perception, a quality of remoteness, a natural sound. The structure words – she (pronoun establishing the subject), could (modal auxiliary indicating possibility or ability), the (definite article pointing to a specific, known thunder) – organize those lexical elements into a precise, grammatically complete statement.

Each word is doing its designated job. The sentence works because lexical meaning and structural meaning are functioning together. As MyEnglishPages’ overview of content words puts it, content words convey the core meaning while function words provide the necessary grammatical framework. Neither type is optional; both are indispensable to coherent communication.

This is ultimately what makes the study of word meaning so rewarding. Language isn’t simply a collection of content – it’s a system. Every word, whether it names a mountain or marks a relationship between two clauses, plays a defined role in that system. Recognizing the difference between what a word means and what a word does grammatically is one of the foundational insights of linguistics, and it opens the door to a much deeper understanding of how human communication works.

What do you think? When you read a sentence with unfamiliar content words but familiar structure words, can you still grasp its overall meaning – and what does that tell you about the relative weight of structural meaning in comprehension? If structure words are a closed class that almost never grows, what happens grammatically when entirely new types of relationships need to be expressed in a language?

References

1. https://en.wikipedia.org/wiki/Lexical_semantics
2. https://en.wikipedia.org/wiki/Function_word
3. https://ecampusontario.pressbooks.pub/essentialsoflinguistics/chapter/7-2-nouns-verbs-and-adjectives-open-class-categories/
4. https://www.grammarly.com/blog/grammar/word-class/
5. https://www.britannica.com/topic/language/Lexical-meaning
6. https://www.languagehumanities.org/what-is-a-function-word.htm
7. http://www.strazny.com/encyclopedia/sample-function-words.html
8. https://teflconcourse.com/training/initial/lexis/functionwords
9. https://ecampusontario.pressbooks.pub/essentialsoflinguistics2/chapter/functional-categories/
10. https://www.ebsco.com/research-starters/language-and-linguistics/lexical-approach
11. https://www.myenglishpages.com/vocabulary-lesson-content-words/