adjective
integral
IN-tih-grul/ˈɪntɪɡrəl/
Necessary to make a whole complete.
The keystone is integral to the stability of the stone arch.

Etymology
The base means “whole”: an integral part belongs to the whole rather than being an optional addition. In this sense, the whole is incomplete or cannot function properly without it.
In context
writing is an integral part of research in the course of writing you realize you don't fully understand some aspects of the work
More examples
- Regular practice is an integral part of learning an instrument.
- Trust is integral to a healthy working relationship.
- Volunteers play an integral role in our food bank.
Forms
integral
integrate verb — Combine separate parts into a unified whole.
Similar words
- essential
- Emphasizes necessity without necessarily describing part of a whole.
- indispensable
- Stresses that something cannot be done without.