- rail (n.1)
- "bar," early 14c., from Old French reille, from Vulgar Latin *regla, from Latin regula "straight stick," diminutive form related to regere "to straighten, guide" (see regal). Used figuratively for "thinness" from 1872. Technically, railings (late 15c.) are horizontal, palings are vertical.
- rail (n.2)
- "small bird," mid-15c., from Old French raale (13c.), related to râler "to rattle," of unknown origin, perhaps imitative.
- rail (v.)
- "complain," mid-15c., from Middle French railler "to tease or joke" (15c.), perhaps from Old Provençal ralhar "scoff, to chat, to joke," from Vulgar Latin *ragulare "to bray" (cf. Italian ragghiare "to bray"), from Late Latin ragere "to roar," probably of imitative origin. See rally (v.2). Related: Railed; railing.