8 letters · 10 points in Scrabble
noun a chemical substance that is present at the start of a chemical reaction
originEtymology tree English react Proto-Indo-European *-onts Latin -ns Latin -āns Old French -antbor. Proto-Indo-European *-onts Proto-Germanic *-ndz Proto-West Germanic *-andī Old English -ende Middle English -ant English -ant English reactant From react + -ant.
Etymology from Wiktionary, CC BY-SA 3.0