disease caused by vitamin D deficiency, 1630s, of uncertain origin (see note in OED). Originally a local name for the disease in Dorset and Somerset, England. Some derive it from a Dorset word, rucket "to breathe with difficulty," but the sense connection is difficult. The Modern Latin name for the disease, rachitis, comes from Greek rhakhis "spine" (see rachitic), but this was chosen by English physician Daniel Whistler (1619-1684) for resemblance to rickets.
chronic disease caused by dietary deficiency (formerly blamed on diseased grain) and characterized by dry, red skin, 1811, from Italian (1770s); according to Watkins, a hybrid formed from Latin pellis "skin" (from PIE root *pel- (3) "skin, hide") + Greek agra "a catching, seizure," related to agrein "to take, seize." But OED suggests it might be originally Italian pelle agra "rough skin." Related: Pellagrous.
c. 1600, "gained by effort," past-participle adjective from acquire. Of diseases, "occurring after birth, thus not dependent on heredity," 1842 (opposed to congenital); acquired immune deficiency is attested by 1980; acquired immune deficiency syndrome by 1982. Acquired taste is attested from 1734.
word-forming element meaning "disease," from Greek nosos "disease, sickness, malady," a word of unknown origin.
late 14c., from Latin supplementum "that which fills up, that with which anything is made full or whole, something added to supply a deficiency," from supplere "to fill up" (see supply (v.)).