Middle English nou, from Old English nu "at the present time, at this moment, immediately; now that," also used as an interjection and as an introductory word; from Proto-Germanic *nu (source also of Old Norse nu, Dutch nu, Old Frisian nu, German nun, Gothic nu "now"), from PIE *nu "now" (source also of Sanskrit and Avestan nu, Old Persian nuram, Hittite nuwa, Greek nu, nun, Latin nunc, Old Church Slavonic nyne, Lithuanian nū, Old Irish nu-). Perhaps originally "newly, recently," and related to the root of new.
Since Old English often merely emphatic, without a temporal sense (as in now then, which is attested from early 13c.). As a noun, "the present time," from late 14c. The adjective meaning "up to date" was revived by 1967, but the word was used also as an adjective with the sense of "current" from late 14c. through 18c. Now and then "occasionally, at one time and another" is from mid-15c.; now or never attested from early 13c. (nu oþer neure).
updated on July 15, 2019