The body

In English you say my head hurts, not the head hurts.

This is different from Spanish, French, Italian and many other languages. Those languages use the, because it is already clear whose head it is. English does not do this. English wants to know whose body part it is, every time.

• I washed my hands.
• He broke his arm.
• She closed her eyes.

If you say I washed the hands, people will understand you, but it sounds wrong.

Two words that change strangely

• one foot, two feet
• one tooth, two teeth

These are the same old pattern you saw with man and men. The sound inside the word changes.

hair is usually one thing

Hair on your head is not counted in English. You say my hair is long, never my hairs are long.

You can count single hairs, but only when you mean one at a time: "There is a hair in my soup."

This is called an uncountable noun. Water, bread and money work the same way.

hurt, pain and sick

Hurt is a verb. "My leg hurts." Pain is a noun. "I have a pain in my leg." Sick and ill are adjectives. "I am sick."

In British English, sick often means you want to vomit. Ill is the safer word for a general illness. In American English, sick means ill and nothing more.

tired

Tired means you need to sleep. Sleepy is close but softer. They are not the same as bored, which means nothing interesting is happening.