When exactly did the meaning of the word gay begin to shift from "having or showing a merry, lively mood; bright or showy" to "homosexual"? During this period, was there evidence of prescriptive resistance toward the new usage, or was it simply a gradual shift towards reinterpreting a metaphorical epithet as the actual definition? i.e.: "He's quite a gal ol' chap, isn't he?" (To the uninitiated: "He's quite a merry, lively ol' chap, isn't he?"; to a member of the subculture: "He's homosexual, isn't he?"). In fact, when did dictionaries first include the "new" definition of gay? Is it still acceptable in any regions/social circles to use the "old" definition?
Is there sign of a similar colloquialism for bisexual emerging?
Finally, in the characteristics of their markedness, is "to not be gay/bisexual", perfectly synonymous with "to be straight"? What are the differing connotations? Is the term ex-gay ("formerly homosexual") in widespread use?
(cross-posted to livejournal_uk)