Meaning

noun a barrier consisting of a horizontal bar and supports

noun short for railway

noun a bar or pair of parallel bars of rolled steel making the railway along which railroad cars or other vehicles can roll

originFrom 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. Doublet of regal, regula, rigol, and rule.

Etymology from Wiktionary, CC BY-SA 3.0