δύο. [36 verses](numeral) "Two" is duo, which means the number "two," "a couple," and "a pair." -- The Greek word for "two" means "two" or a "couple." -- The "twain" is the numeral, "two," which, like numbers in English, plays a lot of roles. Often, it acts as an adjective, but without a noun to modify, so it takes on the role of a noun. The Greek word is "duo," which of course in English means "a pair of singers," or, more generally, any "pair." It uses joins the two people walking together as a pair or a couple.