8 letters · 13 points in Scrabble
adjective participating readily in reactions
adjective reacting to a stimulus
originEtymology tree English react Proto-Indo-European *-wós Proto-Indo-European *-iHwósder. Latin -īvus Old French -ifbor. Middle English -yf English -ive English reactive From react + -ive.
Etymology from Wiktionary, CC BY-SA 3.0