Origin and history of warmly

Old English wearm, "having a moderate degree of heat," from Proto-Germanic *warmaz (source also of Old Saxon, Old Frisian, Middle Dutch, Old High German, German warm, Old Norse varmr, Gothic warmjan "to warm").

A word of uncertain origin. On one guess it is from PIE root *gwher- (source of Greek thermos "warm;" Latin formus "warm," Old English bærnan "to kindle"). On another it is connected to the source of Old Church Slavonic goriti "to burn," varŭ "heat," variti "to cook, boil;" and Lithuanian vérdu, virti "to seethe."

The use of distinct words, based on degree of heat, for warm and hot is general in Balto-Slavic and Germanic, but in other languages one word often covers both (Greek thermos; Latin calidus, French chaud, Spanish caliente).

In reference to feelings, etc., "ardent, full of zeal," it is attested from late 15c. Of colors from 1764. The sense in guessing games of "close to the thing that is sought" is recorded by 1860, probably from earlier use in hunting in reference to the scent or trail (1713).

Warm-blooded in reference to mammals is recorded from 1793. Warm-hearted, "of a generous and affectionate nature, inclined to seek friendship," is by c. 1500.

common adverbial suffix, forming, from adjectives, adverbs signifying "in a manner denoted by" the adjective; Middle English -li, from Old English -lice, from Proto-Germanic *-liko- (source also of Old Frisian -like, Old Saxon -liko, Dutch -lijk, Old High German -licho, German -lich, Old Norse -liga, Gothic -leiko). See -ly (1). It is cognate with lich, and identical with like (adj.).

Weekley notes as "curious" that Germanic uses a word essentially meaning "body" for the adverbial formation, while Romanic uses one meaning "mind" (as in French constamment from Latin constanti mente). The modern English form emerged in late Middle English, probably from influence of Old Norse -liga.