noun · a head full of something, such as sweat, hair, or ideas

他跑完步出了一头大汗。

numeral · doing two things at the same time; concurrently

那个学生一头吃着面包，一头忙着写作业。

numeral · directly, rapidly, or plunging into a place or state

他一头撞在了玻璃门上。

numeral · one end of an object or one side of a situation

这根绳子的一头系在树上。

numeral · one head, often used as a classifier for large animals or livestock

爷爷家养了一头猪。