Wiktionary
n. A game played or used in psychoanalysis in which a word is said out loud and the other person must say the first word they can think of, often as a tool for analysing aspects of the unconscious.
Wikipedia
Word Association is a common word game involving an exchange of words that are associated together. The game is based on the noun phrase word association, meaning "stimulation of an associative pattern by a word" or "the connection and production of other words in response to a given word, done spontaneously as a game, creative technique, or in a psychiatric evaluation."
Usage examples of "word association".
In the volume Disorders of Communication, Miller describes experiments using word association tests to compare normals and schizophrenics.
Anyway, word association, you say lobbyist and I say rotund, foxy, devious, green-backs, call girls, et cetera.