rail (n.1)

"horizontal bar passing from one post or support to another," c. 1300, from Old French raille, reille "bolt, bar," from Vulgar Latin *regla, from Latin regula "rule, straight piece of wood," diminutive form related to regere "to straighten, guide" (from PIE root *reg- "move in a straight line").

 In U.S. use, "A piece of timber, cleft, hewed, or sawed, inserted in upright posts for fencing" [Webster, 1830]. Used figuratively for thinness from 1872. By 1830s as "iron or steel bar or beam used on a railroad to support and guide the wheels." To be off the rails "out of the normal or proper condition" in a figurative sense is from 1848, an image from railroads.

rail (n.2)

"small wading bird," mid-15c., rale, from Old French raale (13c.), related to râler "to rattle," which is of unknown origin, perhaps imitative; the bird would be so called for its cry.

rail (v.1)

"complain, speak vehemently and bitterly," late 15c., railen, from Old French raillier "to tease or joke" (15c.), which is perhaps from Old Provençal ralhar "scoff, to chat, to joke," from Vulgar Latin *ragulare "to bray" (source also of Italian ragghiare "to bray"), from Late Latin ragere "to roar," probably of imitative origin. See rally (v.2). Related: Railed; railing.

rail (v.2)

"fence in or enclose with rails," late 14c., railen, from rail (n.1). Related: Railed; railing.

Definitions of rail
rail (v.)
complain bitterly;
Synonyms: inveigh
rail (v.)
enclose with rails;
rail in the old graves
Synonyms: rail in
rail (v.)
provide with rails;
The yard was railed
rail (v.)
separate with a railing;
rail off the crowds from the Presidential palace
Synonyms: rail off
rail (v.)
convey (goods etc.) by rails;
fresh fruit are railed from Italy to Belgium
rail (v.)
travel by rail or train;
They railed from Rome to Venice
Synonyms: train
rail (v.)
lay with rails;
hundreds of miles were railed out here
rail (v.)
fish with a handline over the rails of a boat;
They are railing for fresh fish
rail (v.)
spread negative information about;
Synonyms: vilify / revile / vituperate
rail (v.)
criticize severely;
She railed against the bad social policies
Synonyms: fulminate
rail (n.)
a barrier consisting of a horizontal bar and supports;
Synonyms: railing
rail (n.)
short for railway;
he was concerned with rail safety
he traveled by rail
rail (n.)
a bar or pair of parallel bars of rolled steel making the railway along which railroad cars or other vehicles can roll;
Synonyms: track / rails / runway
rail (n.)
a horizontal bar (usually of wood or metal);
rail (n.)
any of numerous widely distributed small wading birds of the family Rallidae having short wings and very long toes for running on soft mud;