essential part
noun phraseUK /ɪˈsen.ʃəl pɑːt/
US /ɪˈsen.ʃəl pɑːrt/
A thing you must have because you cannot do without it.
The wheels are an essential part of a bicycle.
RELATED WORDS
OTHER MEANINGS
2. The most important piece of something.
Trust is the essential part of a good friendship.
3. A part that cannot be left out.
Water is an essential part of every living thing.
4. A basic building block of a whole.
The engine is the essential part of the car.