slothful adj.

late 12c., slouthe, "indolence, sluggishness, neglect of responsibilities," formed from Middle English slou, slowe (see slow (adj.)) + abstract formative -th (2).

It displaced earlier sleuthe, from Old English slæwþ, Kentish slewð, "sloth, indolence." The modern form might also be the old word conformed to the vowel in the adjective. The modern sense of "slowness, tardiness" is attested from mid-14c. As one of the deadly sins, it translates Latin accidia. A sloth-salve (c. 1400) was a (figurative) remedy for indolence.

The slow-moving South American mammal was first so called 1610s, a translation of Portuguese preguiça "slowness, slothfulness," from Latin pigritia "laziness" (compare Spanish perezosa "slothful," also "the sloth").

word-forming element attached to nouns (and in modern English to verb stems) and meaning "full of, having, characterized by," also "amount or volume contained" (handful, bellyful); from Old English -full, -ful, which is full (adj.) become a suffix by being coalesced with a preceding noun, but originally a separate word. Cognate with German -voll, Old Norse -fullr, Danish -fuld. Most English -ful adjectives at one time or another had both passive ("full of x") and active ("causing x; full of occasion for x") senses.

It is rare in Old English and Middle English, where full was much more commonly attached at the head of a word (for example Old English fulbrecan "to violate," fulslean "to kill outright," fulripod "mature;" Middle English had ful-comen "attain (a state), realize (a truth)," ful-lasting "durability," ful-thriven "complete, perfect," etc.).

word-forming element meaning "state or condition of being," from Old English -had "condition, quality, position" (as in cildhad "childhood," preosthad "priesthood," werhad "manhood"), cognate with German -heit/-keit, Dutch -heid, Old Frisian and Old Saxon -hed, all from Proto-Germanic *haidus "manner, quality," literally "bright appearance," from PIE (s)kai- (1) "bright, shining" (Cognates: Sanskrit ketu "brightness, appearance"). Originally a free-standing word (see hade); in Modern English it survives only in this suffix.