suffix used to make jocular or familiar formations from common or proper names (soccer being one), first attested 1860s, English schoolboy slang, "Introduced from Rugby School into Oxford University slang, orig. at University College, in Michaelmas Term, 1875" [OED, with unusual precision].
1530s, "action of coming together for a common purpose," from Medieval Latin associationem (nominative associatio), noun of action from past-participle stem of associare "join with," from assimilated form of ad "to" (see ad-) + sociare "unite with," from socius "companion, ally" (from PIE *sokw-yo-, suffixed form of root *sekw- (1) "to follow"). Meaning "an organized body of persons with a common purpose" is from 1650s. Meaning "mental connection" is from 1680s; that of "quality or thing called to mind by something else" is from 1810.