early 14c., "destructive," from waste (n.) + -ful. Meaning "lavish" is from mid-15c. Related: Wastefully; wastefulness.
Entries linking to wasteful
waste n.
c. 1200, "desolate regions," from Anglo-French and Old North French wast "waste, damage, destruction; wasteland, moor" (Old French gast), from Latin vastum, neuter of vastus "empty, desolate," from PIE *wasto-, extended suffixed form of root *eue- "to leave, abandon, give out."
Replaced or merged with Old English westen, woesten "a desert, wilderness," from the Latin word. Meanings "consumption, depletion," also "useless expenditure" are from c. 1300; sense of "refuse matter" is attested from c. 1400. Waste basket first recorded 1850.
-ful
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.).