Y-fronts

n [pl] (Brit propr 专利名) men's underpants, with seams and an opening in the front sewn in the shape of an inverted Y 男用内裤（前有倒Y形开口者）: a pair of Y-fronts 一条男用内裤（前有倒Y形开口者）.

WWF, WX, wych-elm, x, X (also x), X chromosome, X, x, X-ray, xenon, xenophobe, xenophobia, xenophobic, Xerox, Xhosa, XL, Xmas, Xt, Y, Y chromosome, Y, y, yacht, yachtsman, yack, yackety-yack, yah, yahoo, yak, Yale, yam, yammer, yang, Yank, Yankee, yap, yard, yard of ale, yard-arm, yardage, yardstick, yarmulka,