Maybe it only makes sense that this would be the case, but English has a lot of words to talk about language. There’s slang, dialect, palaver, jargon, argot, colloquial, vernacular, vocabulary and, most importantly here, lexicon. Each of these terms has a slightly different usage, but we don’t blame you if you’re not entirely sure which is which. So, what does the word lexicon mean? Let’s dive in.

What Is A Lexicon In General?

The word “lexicon” has a somewhat flexible meaning. It can be applied to an entire language — the Italian lexicon encompasses all Italian words — or it can refer to a subset. For example, a group of engineers might have a lexicon they use to talk about their work. You can have a subject-specific lexicon, like a movie lexicon or a math lexicon. In most cases, then, lexicon is a synonym for vocabulary.

In certain circumstances, lexicon can have a less vague meaning. For example, a lexicon is another word for a dictionary (though it’s not nearly as commonly used for one). When used in this sense, you can also talk about lexiconists, which is a word for the person who writes a lexicon. 

In other cases, it can be even vaguer, and people use it to describe non-language concepts. A person might refer to their “book lexicon” as a way to describe all the books they know. This might not make as much sense — lexicon is historically related to language — but you can’t stop the evolution of a word’s meaning.

What Is A Lexicon In Linguistics?

One important case where the word “lexicon” is more specifically relevant is within the field of linguistics. In fact, linguists divide languages into two parts: the lexicon and the grammar. The grammar is the set of rules that govern how language works: things like word order and conjugation are all defined by these rules. The lexicon, at its broadest, is the collection of everything else. To be more specific, it’s the full collection of lexemes.

A lexeme — sometimes called a lexical item or a word form — is a basic unit of meaning in language. Most lexemes are single words, and a single lexeme includes all conjugations of a word. Eat, ate and eating, for example, are all a single lexeme. The difference between “lexeme” and “word,” however, is that a lexeme can also be more than one word. Compound nouns and verbs (living room, eat up) and idioms (hit the hay, once in a blue moon) also count as lexemes because their meaning changes if you break them down into smaller parts. It can also be noted that, as with pretty much all linguistic topics, there is debate over what should count as a lexeme. For the average person, though, all you really need to know is that a lexicon contains all the basic words and phrases that make up a language.

If you’re looking for a connection between a lexicon and language learning, then, the two are pretty inextricable. It comprises all the words you’ll be learning to understand the language. It’s likely that you’ll probably hear the word “vocabulary” more often, but even so, it’s worth knowing exactly what a lexicon is.