c. 1200, "devastate, ravage, ruin," from Anglo-French and Old North French waster "to waste, squander, spoil, ruin" (Old French gaster; Modern French gâter), altered (by influence of Frankish *wostjan) from Latin vastare "lay waste," from vastus "empty, desolate," from PIE *wasto-, extended suffixed form of root *eue- "to leave, abandon, give out." Related: wasted; wasting.
The Germanic word also existed in Old English as westan "to lay waste, ravage." Spanish gastar, Italian guastare also are from Germanic. Meaning "to lose strength or health; pine; weaken" is attested from c. 1300; the sense of "squander, spend or consume uselessly" is first recorded mid-14c.; meaning "to kill" is from 1964. Waste not, want not attested from 1778.