Old English eorþlic "worldly, pertaining to this world" (as opposed to spiritual or heavenly); see earth (n.) + -ly (1). The sense "belonging to or originating in the earth" is from mid-15c.
Entries linking to earthly
earth n.
Old English eorþe "ground, soil, dirt, dry land; country, district," also used (along with middangeard) for "the (material) world, the abode of man" (as opposed to the heavens or the underworld), from Proto-Germanic *ertho (source also of Old Frisian erthe "earth," Old Saxon ertha, Old Norse jörð, Middle Dutch eerde, Dutch aarde, Old High German erda, German Erde, Gothic airþa), perhaps from an extended form of PIE root *er- (2) "earth, ground."
The earth considered as a planet was so called from c. 1400. Use in old chemistry is from 1728. Earth-mover "large digging machine" is from 1940.
-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).
unearthly adj.
1610s, "heavenly, sublime," from un- (1) "not" + earthly. Sense of "ghostly, weird" is attested by 1802. Related: Unearthliness.