"easy," 1915, Anglo-Indian slang, from Hindi khush "pleasant, healthy, happy" + -y (2). Wright's "English Dialect Dictionary" (1898) has cush "a soft, useless person," identified as Scottish and Northumberland and explained as "A common term of reproach, used of one who allows others to beat him, either in self-defence or at work," hence cushie "soft, flabby."
In early 19th century use, a stage-play (usually romantic and sentimental in plot and incident) in which songs were interspersed and in which the action was accompanied by orchestral music appropriate to the situations. In later use the musical element gradually ceased to be an essential feature of the 'melodrama', and the name now denotes a dramatic piece characterized by sensational incidents and violent appeals to the emotions, but with a happy ending. [OED]
The shift toward "a romantic and sensational dramatic piece with a happy ending" is evident by 1883. Also from French are Spanish melodrama, Italian melodramma, German melodram. Related: Melodramatize.
The melodramatist's task is to get his characters labelled good & wicked in his audience's minds, & to provide striking situations that shall provoke & relieve anxieties on behalf of poetic justice. [Fowler]
"device by means of which a catch or spring is released and a mechanism set in action," 1650s, earlier tricker (1620s), from Dutch trekker "trigger," from trekken "to pull" (see trek). Tricker was the usual form in English until c. 1750. Trigger-finger "forefinger as used to pull the trigger of a gun" is attested by 1814. Trigger-happy "ready to shoot (or otherwise react violently) on the slightest provocation" is attested from 1942.
It forms all or part of: acquiesce; acquit; awhile; coy; quiesce; quiescent; quiet; quietism; quietude; quietus; quit; quitclaim; quite; quit-rent; quittance; requiescat; requiem; requite; while; whilom.
It is the hypothetical source of/evidence for its existence is provided by: Avestan shaitish "joy," shaiti- "well-being," shyata- "happy;" Old Persian šiyatish "joy;" Latin quies "rest, repose, quiet;" Old Church Slavonic po-koji "rest;" Old Norse hvild "rest."