Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
reign, rain, rein (nn., vv.)
These homophones differ in meaning and spelling. Of the nouns, a reign is “a monarch’s power or period of rule,” a rein is “one of the paired leather straps (reins) fastened to the bit in the horse’s mouth, by means of which you steer it,” and rain is “the water that falls from the heavens.” Of the verbs, to reign is “to rule a nation as its monarch,” to rein is “to steer a horse or team” (and to rein in is “to cause the horse or team to slow or stop” and, figuratively, “to steer, slow, or stop almost anything”), and to rain is what the weather does on picnics.
