early 15c., "full of misery, causing wretchedness" (of conditions), from Old French miserable (14c.) and directly from Latin miserabilis "pitiable, miserable, deplorable, lamentable," from miserari "to pity, lament, deplore," from miser "wretched" (see miser). Of persons, "existing in a state of want, suffering, wretchedness, etc.," it is attested from 1520s. Meaning "mentally full of misery, wretched in feeling unhappy," by 1590s. Related: Miserableness.
The sense associated with miser, "covetous, miserly," is attested from late 15c., but by 1895 (Century Dictionary) was "obsolete or Scotch." As a noun, "an unfortunate, an unhappy creature," 1530s (reinforced later by the French cognate, as in Hugo's "Les Misérables").
common adverbial suffix, forming from adjectives adverbs signifying "in a manner denoted by" the adjective, Middle English, from Old English -lice, from Proto-Germanic *-liko- (cognates: Old Frisian -like, Old Saxon -liko, Dutch -lijk, Old High German -licho, German -lich, Old Norse -liga, Gothic -leiko); see -ly (1). 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.