8 letters · 12 points in Scrabble
originFrom Middle English senight, senyght, sinight (“sevennight, a week”) [and other forms], a shortened form of seven-night, sevenight, sevenyght [and other forms], from Late Old English seofeniht (compare seofonnihte (“seven days old; seven days long”, adjective)), from seofon (“seven”) (ultimately from Proto-Indo-European *septḿ̥ (“seven”)) + niht (“night; day (when computing spans of time)”)…
Etymology from Wiktionary, CC BY-SA 3.0