round the bend

Old English bendan "to bend a bow; confine with a string, fetter," causative of bindan "to bind," from Proto-Germanic base *band- "string, band" (cf. Old Norse benda "to join, strain, strive, bend"), from PIE root *bhendh- "to bind" (cf. Gothic bindan, Old High German bintan, Sanskrit badhnati "binds," Lithuanian bendras "partner;" Old Persian bandaka- "subject").

Modern sense (early 14c.) is via notion of bending a bow to string it. Cognate with band, bind, and bond. Related: Bended; bent; bending.