What is a lexeme? (The heart of a word)

Think of a lexeme as the basic idea or main meaning of a word. It's like the "boss" version that doesn't change even if the word looks a little different.

For example, the word cat can be just one cat or lots of cats (singular or plural), but in our mind (and in dictionaries), the idea of what a cat is stays the same whether it’s one or many. It covers cat and cats. We don't need a separate dictionary page for ‘cats’ – it's just the plural of the same idea.

Another way of thinking about is this. A set of forms for a root word.

Example

Cat (singular form)

Cats (plural form)

2 forms of the same word = a set

Dictionaries usually show the simple "base" form (like "cat") because that's the lexeme the root (the heart).

Two tricky things: same spelling, different meanings

#1.

Polysemy – the capacity for a single word or phrase to have related meanings. One word idea can grow extra meanings that are connected.

Example

A mouse (the animal). But it’s also the thing you use to click on your computer  so we call the computer thing a "mouse" too. It's the same lexeme MOUSE with two related meanings.

#2.

Homonymy – a word/phrase with totally different meanings that just happens to look/sound the same. These are like strangers who share the same name. They get their own separate dictionary entries.

Example

Pen = thing you write with, or, a small fenced area for animals. Horses, pigs, goats, chickens.

Date = the fruit, or, a day on the calendar Totally unrelated, or a date with someone special

And here are some other words you should be aware off too

Lexis or vocabulary

All the words in a language (or just in one topic, like ‘doctor words’ or ‘computer words’).

Lexical set

A little family of similar words, e.g., apple, banana, orange (all fruits).

Lexicon

The whole big collection of words in English (or sometimes just means "dictionary").