clevis (n.)

"U-shaped iron bar with holes at the ends for a bolt or pin, used as a fastener," 1590s, of unknown origin; perhaps from a Scandinavian source akin to Old Norse klofi "a cleft," from Proto-Germanic *klub‑ "a splitting," from PIE root *gleubh- "to tear apart, cleave." Also uncertain is whether it is originally a plural or a singular.