可能来自拉丁语fatuus, 无味的,愚笨的,词源同fatuous. 原用于食物清淡无味,后用于光线逐渐变暗。
Adieu! adieu! thy plaintive anthem fades
Past the near meadows, over the still stream,
Up the hill-side; and now 'tis buried deep
In the next valley-glades:
Was it a vision, or a waking dream?
Fled is that music:--Do I wake or sleep?
[Keats, "Ode to a Nightingale"]