Ruck: From Old Norse hrukka (wrinkle, fold). Ultimately from the Indo-European root sker- (to turn or bend), which is also the source of ranch, rank, shrink, circle, circa, crisp, corolla, search, ring, curb, ridge, curve, corolla, and coronary.
"Writhe"
wound its way to English from the Old English verb "wrīthan" ("to twist") and is
akin to the Old English verb "wrigian" ("to turn or go").
"Wrigian" gave us our words "wriggle," "awry,"
and "wry."
