Emily Dickinson Lexicon

RAIN, v.i. [Sax. hregnan, regnan, renian, rinan, to rain; Goth. rign, rain; Sax. racu; Cimbric, raekia, rain; D. and G. regen, rain; D. regenen, to rain; Sw. regn, rain; regna, to rain; Dan. regn, rain; regner, to rain; G. beregnen, to rain on. It seems that rain is contracted from regen. It is the Gr. βρεχω, to rain, to water, which we retain in brook, and the Latins, by dropping the prefix, in rigo, irrigo, to irrigate. The primary sense is to pour out, to drive forth, Ar. بَرَكَ baraka, coinciding with Heb. Ch. and Syr. ברך. Class Brg, No. 3.]

1. To fall in drops from the clouds, as water; used mostly with it for a nominative; as, it rains; it will rain; it rained, or it has rained.
2. To fall or drop like rain; as, tears rained at their eyes. – Milton.