12 letters · 20 points in Scrabble
adverb without advance planning
adverb of a minor or subordinate nature
adverb without intention; in an unintentional manner
originEtymology tree English accidental Proto-Indo-European *leyg-der. Proto-Germanic *līkąder. Proto-Germanic *-līkaz Proto-Germanic *-ê Proto-Germanic *-līkê Proto-West Germanic *-līkē Old English -līċe Middle English -ly English -ly English accidentally From accidental + -ly.
Etymology from Wiktionary, CC BY-SA 3.0