Other forms: rails, railing, railed
A rail is a long straight bar fixed in place — the two steel ones a train's wheels run along, or the one you grab going down the stairs. Hands sliding along the rail of a staircase, a wet towel over the heated rail in the bathroom, a curtain rail sagging in the middle.
Travel by rail is travel by train, and rail names the whole industry: rail fares, a rail strike, a rail replacement bus on a Sunday. When a plan or a person goes off the rails, the picture is a train leaving the track. A railing is the fence several rails make together — the black railings outside a London house. There is also a verb, and it has nothing to do with bars: to rail against something is to attack it in loud, bitter words. Handrail, guardrail, towel rail, curtain rail: each compound is one bar doing one job.
1nounrailOne of the steel bars that a train's wheels run along.
“The wheels squealed on the wet rails as the train came into the station.”
2nounhandrailA bar fixed in place for holding onto or for hanging things from.
“She kept one hand on the rail all the way down the icy steps.”
3nounsystemThe railway system, seen as a way of travelling or of moving goods.
“We sent the parcels by rail because the roads were closed.”
4verbrantTo complain about something loudly and bitterly.
“He railed against the new parking charges at every meeting.”
rail is a bar.
Rail traces back to Latin regula, a rule or straight bar, from regō, to rule or guide. It reached English twice over — through Old French reille and through Old English regol, a straight measuring bar, which Middle English used in reȝolsticke, a ruler. So rail and rule are the same word in different clothes, and both begin as something perfectly straight.
Old English
regol
Middle English
rail
English, today
rail
Built from
From Middle English rail, from Old English regol. From Middle English rail, rayl, reȝel, reȝol (found in reȝolsticke (“a ruler”)), partly from Old English regol (“a ruler, straight bar”) and partly from Old French reille; both from Latin regula (“rule, bar”), from regō (“to rule, to guide, to govern”); see regular. a doublet of regal#Noun and regula and rigol and rule.
Etymology from Wiktionary, CC BY-SA