Collocability of words that is their ability to combine with other words in speech is based on their valency. Valency and collocability may be lexical and grammatical, or syntactical.
The aptness of a word to be used in certain grammatical or syntactical pattern is called grammatical valency. In other words grammatical valency is the possibility of syntactical connection of a word on the syntactical level. Grammatical or syntactical collocability is the realization of the grammatical valency in speech which is achieved through lexical collocability. Lexical valency is the aptness of a word to appear in various combinations with other words in speech. Lexical valency is the possibility of connecting a word with other words on the lexico-semantic level. Lexical collocability is the realization of lexical valency in speech. Valency and collocability are linguistic factors that determine the co-occurrence of English words, but they are not the only factors that influence the co-occurrence of words in speech.
