Keyness

Keyness is a term used in linguistics to describe the quality a word or phrase has of being "key" in its context. Compare this with collocation, the quality linking two words or phrases usually assumed to be within a given span of each other. Keyness is a textual feature, not a language feature (so a word has keyness in a certain textual context but may well not have keyness in other contexts, whereas a node and collocate are often found together in texts of the same genre so collocation is to a considerable extent a language phenomenon). The set of keywords found in a given text share keyness, they are co-key. Words typically found in the same texts as a key word are called associates.

References

Scott, M. & Tribble, C., 2006, Textual Patterns: keyword and corpus analysis in language education, Amsterdam: Benjamins, especially chapters 4 & 5.