What is the origin of felicitous?
Felicitous “well-suited for the occasion,” based on the noun felicity “happiness; skillful faculty,” derives from Latin fēlīcitās “good luck, happiness.” Fēlīcitās comes from the adjective fēlīx (stem fēlīci-) “lucky, happy,” plus the noun-forming suffix -tās “-ness.” Fēlīx and its descendants in modern Romance languages show a common pattern, namely, that a word for “lucky” in a mother language eventually gains the additional sense of “happy,” and either the “happy” sense alone or, less often, both senses are preserved in a daughter language. We can see this tendency when we compare Latin fēlīx “lucky, happy” with Spanish feliz “happy” and Italian felice “happy, lucky” (though the “lucky” sense in Italian is only in certain contexts). A stronger example lies in the English language itself, in which happy derives from the noun hap “luck,” which is also the source of the verb happen. Felicitous was first recorded in English circa 1730.