1540s (adj.), 1630s (adv.), from easter (late 14c.), variant of eastern + -ly (1) and (2). As a noun meaning "easterly wind," by 1901. Old English easterlic meant "pertaining to Easter."
Entries linking to easterly
eastern adj.
Old English easterne "of the east, from the east; oriental; of the Eastern Orthodox Church; of the eastern part of the globe," from east + -erne, suffix denoting direction. Cognate with Old Saxon ostroni, Old High German ostroni, Old Norse austroenn. Eastern Shore of Maryland and Virginia so called from 1620s.
-ly 1
suffix forming adjectives from nouns and meaning "having qualities of, of the form or nature of" (manly, lordly), "appropriate to, fitting, suited to" (bodily, earthly, daily); irregularly descended from Old English -lic, from Proto-Germanic *-liko- (Old Frisian -lik, Dutch -lijk, Old High German -lih, German -lich, Old Norse -ligr), related to *likom- "appearance, form" (Old English lich "corpse, body;" see lich, which is a cognate; see also like (adj.), with which it is identical).
northerly
1550s as an adjective, "pertaining to or being in or toward the north; proceeding from the north," from northern + -ly (2) on pattern of easterly, westerly. As an adverb, "toward the north," from 1590s. Related: Northerliness.