enkindle (v.)

word-forming element meaning "in; into," from French and Old French en-, from Latin in- "in, into" (from PIE root *en "in"). Typically assimilated before -p-, -b-, -m-, -l-, and -r-. Latin in- became en- in French, Spanish, Portuguese, but remained in- in Italian.

Also used with native and imported elements to form verbs from nouns and adjectives, with a sense "put in or on" (encircle), also "cause to be, make into" (endear), and used as an intensive (enclose). Spelling variants in French that were brought over into Middle English account for parallels such as ensure/insure, and most en- words in English had at one time or another a variant in in-, and vice versa.

c. 1200, cundel, "to set fire to, to start on fire," probably from a Scandinavian source akin to Old Norse kynda "to kindle, to light a fire," Swedish quindla "kindle," all of uncertain origin, + frequentative suffix -le. Figurative use (of feelings, passions, etc.) is from c. 1300. Intransitive sense "to begin to burn, to catch fire" is from c. 1400. Related: Kindled; kindling.

Modern sources do not connect it to Latin candela. In the literal sense, Old English had ontyndan "kindle, set fire to," from tendan "to kindle" (see tinder). The word was influenced in form, and sometimes in Middle English in sense, by kindel "to give birth" (of animals), "bring forth, produce" (c. 1200), from kindel (n.) "offspring of an animal, young one," from Old English gecynd (see kind (n.)) + -el.