13 letters · 20 points in Scrabble
adverb without knowledge or intention
originEtymology tree Medieval Latin inadvertēnsbor. English inadvertent 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 inadvertently From inadvertent + -ly.
Etymology from Wiktionary, CC BY-SA 3.0