mid-14c., "place where one lives or dwells," also "general course of actions or habits, manner of conducting oneself in the world," both senses now obsolete; from Old French conversacion "behavior, life, way of life, monastic life," and directly from Latin conversationem (nominative conversatio) "frequent use, frequent abode in a place, intercourse, conversation," noun of action from past-participle stem of conversari "to live, dwell, live with, keep company with," passive voice of conversare "to turn about, turn about with," from assimilated form of com "with, together" (see con-) + versare, frequentative of vertere "to turn" (from PIE root *wer- (2) "to turn, bend").

Sense of "informal interchange of thoughts and sentiments by spoken words" is from 1570s. Used as a synonym for "sexual intercourse" from at least late 14c., hence criminal conversation, a legal term for adultery from late 18c. Conversation-piece is from 1712 as "painting representing a group of figures arranged as if in conversation;" 1784 as "subject for conversation, something to talk about."

"of, pertaining to, or characteristic of conversation," 1779, from conversation + -al (1).

"have conversation," attested by 1888 in literary representations of African-American vernacular, apparently a back-formation from conversation or an elaboration of converse (v.). There is an isolated, jocular use in an English book from 1851.

1751, "pertaining to conversation," from colloquy "a conversation" + -al (1). From 1752 as "peculiar or appropriate to the language of common speech or familiar conversation," especially as distinguished from elegant or formal speech. Related: Colloquially.

1640s, "of or having to do with sermons," from Late Latin homileticus, from Greek homiletikos "of conversation, affable," from homilia "conversation, discourse," in New Testament, "sermon" (see homily). Related: Homiletical.

mid-15c., "a discourse," from Latin colloquium "conference, conversation," literally "a speaking together," from assimilated form of com "together" (see com-) + -loquium "speaking," from loqui "to speak" (from PIE root *tolkw- "to speak"). Meaning "conversation" is attested in English from 1580s.

1640s, "relating to the art of reasoning about probabilities," from Latin dialecticus, from Greek dialektikos "of conversation, discourse," from dialektos "discourse, conversation" (see dialect). From 1813 as "of or pertaining to a dialect or dialects." 

"session of conversation," 1895, American English colloquial, from gab + -fest.

c. 1600, "conversation, dialogue" (a sense now obsolete), from Latin colloquium "conference, conversation," literally "a speaking together," from com- "together" (see com-) + -loquium "speaking," from loqui "to speak" (from PIE root *tolkw- "to speak"). Also as a legal term; meaning "a meeting for discussion, assembly, conference, seminar" is attested by 1844.

also daliance, mid-14c., daliaunce "edifying or spiritual conversation," from dally + -ance. Probably formed in Anglo-French but not attested there. From late 14c. as "polite conversation, chat, small talk; amorous talk, flirtation, coquetry;" meaning "idle or frivolous activity" is from 1540s.