hum /hʌm/ I. vt. & vi.(hummed; humming) 1. （蜜蜂等）发出嗡嗡声；（人等）发出哼声：The motor hummed pleasantly. 发动机发出令人愉快的声音。She was humming to herself.她独自哼着歌。2. 忙碌，有活力（口语）：Things are starting to hum(=with activity).事情即将要有活力。‖II. n.(可用a,不可用one 或 pl.) 嗡嗡声，吵杂声：the hum of bees蜜蜂的嗡嗡声；quiet the hum of day noises使白天的吵杂声平静下来