In lexicography, a lexical item is a single word, a part of a word, or a chain of words (catena) that forms the basic elements of a language's lexicon (≈ vocabulary). Examples are cat, traffic light, take care of, by the way, and it's raining cats and dogs. Lexical items can be generally understood to convey a single meaning, much as a lexeme, but are not limited to single words. Lexical items are like semes in that they are "natural units" translating between languages, or in learning a new language. In this last sense, it is sometimes said that language consists of grammaticalized lexis, and not lexicalized grammar. The entire store of lexical items in a language is called its lexis.
Lexical items composed of more than one word are also sometimes called lexical chunks, gambits, lexical phrases, lexicalized stems, or speech formulae. The term polyword listemes is also sometimes used.
Common types of lexical items/chunks include:
Words, e.g. cat, tree
Parts of words, e.g. -s in trees, -er in worker, non- in nondescript, -est in loudest
Phrasal verbs, e.g. put off or get out
Multiword expressions, e.g. by the way, inside out
Collocations, e.g. motor vehicle, absolutely convinced.
Institutionalized utterances, e.g. I'll get it, We'll see, That'll do, If I were you, Would you like a cup of coffee?
Idioms, e.g. break a leg, was one whale of a, a bitter pill to swallow
Sayings, e.g. The early bird gets the worm, The devil is in the details
Sentence frames and heads, e.g. That is not as...as you think, The problem was
Text frames, e.g., In this paper we explore...; First...; Second...; Lastly....
An associated concept is that of noun-modifier semantic relations, wherein certain word pairings have a standard interpretation. For example, the phrase cold virus is generally understood to refer to the virus that causes a cold, rather than to a virus that is cold.
Many lexical items are either a whole word or part of a word, whereas many other lexical items consist of parts of one or more words or of multiple words in their entirety.