nod

n. letting head fall forward in drowsiness,drowsi-ness,momentary lack of attention,making a carelessslip（瞌睡时的）一歪头，瞌睡，一不留心，疏失。
△R.III.3.4.99(100): “Ready with every nod to tumble down /Into the fatal bowels of the deep.”稍一打瞌睡，就立刻会翻滚下去，掉进大海的毁灭性的深渊。

nod[nɔd]

v.& n.点头
◇ a nod is as good as a wink不必明言
have a nodding acquaintance with sb. (sth.)对某事物略知一二
nod off睡着on the nod未经同意表示赞成