11 letters · 13 points in Scrabble
verb give extra weight to (a communication)
verb draw a line or lines underneath to call attention to
originEtymology tree Proto-Indo-European *h₁én Proto-Indo-European *h₁entér Proto-Indo-European *(H)n̥dʰí Proto-Indo-European *-ér Proto-Indo-European *(H)n̥dʰér Proto-Germanic *under Proto-West Germanic *undar Old English under- Middle English under- English under- English lining English underlining From under- + lining.
Etymology from Wiktionary, CC BY-SA 3.0