Everyday talk treats words as obvious units, yet boundaries can be tricky. A word is a linguistic unit that can typically stand alone, carries meaning, and is separated by spaces in the orthography of many languages—though linguistic tests go beyond spelling.

Words combine morphemes and serve as heads of phrases. Languages differ in whether they prefer many short words or long multimorphemic words. Psycholinguistic experiments probe how words are stored and accessed in the mental lexicon.

Dictionaries take the word as their primary listing unit, with allowances for multiword expressions. Defining wordhood cross-linguistically remains a theoretical challenge, but the unit remains indispensable for description, literacy, and ordinary metalanguage.

• Standalone meaningful linguistic unit
• Built from one or more morphemes
• Orthographic and linguistic criteria sometimes diverge
• Central to lexicography and everyday talk about language