Meaning

noun a quantity that is added

noun the advantageous quality of being beneficial

noun the amount of increase in signal power or voltage or current expressed as the ratio of output to input

originFrom Middle English gayn, gain, gein (“profit, advantage”), from Old Norse gagn (“benefit, advantage, use”), from Proto-Germanic *gagną, *gaganą (“gain, profit", literally "return”), from Proto-Germanic *gagana (“back, against, in return”), a reduplication of Proto-Germanic *ga- (“with, together”), from Proto-Indo-European *ḱóm (“next to, at, with, along”). Cognate with Icelandic gagn (“gain,…

Etymology from Wiktionary, CC BY-SA 3.0