under your breath this idiom, first recorded in 1832, is probably a hyperbole, alluding to a sound that is softer than breathing 这个成语最早出现在1832年，可能是一种夸张的说法，暗指一种比呼吸还柔和的声音 quietly so that other people cannot hear exactly what you are saying 低声地，轻声地 He muttered something under his breath. 他低声嘀咕着什么。