英语词源字典 - 在线词源网站

finicky (adj.)[finicky 词源字典]: 1825, "dainty, mincing," from finical "too particular" (1590s), which perhaps is from fine (adj.) + -ical as in cynical, ironical (OED says "ultimate derivation" from the adjective "seems probable"). But finikin (1660s) "dainty, precise in trifles" has been proposed as a source, even though the timing is off. It apparently comes from Dutch; compare Middle Dutch fijnkens (adv.) "precisely, exactly," from fijn, cognate with English fine (adj.).

The -k- between the final -c- and a suffix beginning in -i, -y, or -e is an orthographic rule to mark the pronunciation of -c- as "k" (compare picnicking, trafficking, panicky, shellacked). Related: Finickiness.[finicky etymology, finicky origin, 英语词源]
picnic (v.): "go on a picnic," 1842, from picnic (n.). Related: Picnicked; picnicking. The -k- is inserted to preserve the "k" sound of -c- before a suffix beginning in -i-, -y-, or -e- (compare traffic/trafficking, panic/panicky, shellac/shellacked).
shellac (v.): 1876, from shellack (n.). The slang sense of "beat soundly" is 1920s, perhaps from the notion of shellac as a "finish." Shellacked "drunk" is from 1922 (compare plastered). Related: Shellacking.
traffic (v.): 1540s, "to buy and sell," from traffic (n.) and preserving the original commercial sense. Related: Trafficked; trafficking; trafficker. The -k- is inserted to preserve the "k" sound of -c- before a suffix beginning in -i-, -y-, or -e- (compare picnic/picnicking, panic/panicky, shellacshellacked).