英和和英

to rack one's brains―cudgel one's brains―worry （oneself）

to cause trouble for someone

to think very deeply about something

to beat one's brains―cudgel one's brains―rack one's brains―ransack one's brains

to scratch one's head―（恥じてなら）―hang one's head for shame

to cut one's hair

to make a great effort of the mind in order to understand or find the answer to a difficult question

I want （to have） my hair cut.

the function of the brain

I am going to have my hair cut.

I'm a bit out of it.

the nod of a head

to beat one's brains―cudgel one's brains―rack one's brains―ransack one's brains

to lower one's head

My head throbs.

He/She is really clever.

the condition of being smart and quick to understand

I feel out of it.

a precise mind

My head whirls.

the head of a member of the Japanese nobility

to bow one's head―incline one's head

My head itches

a level head

Use your bean.

a white head

to lay one's head on the pillow―recline one's head on the pillow

of a person, to become mentally deranged

have a thick head

Aren't I clever?