There are many different traditions & many different definitions of meditation.

Angel City Zen Center provides a description of how to sit zazen. It might be summed up as: sitting, & paying attention to what is happening in the body & mind without judging it.

Hinduism uses the term dhyana. Buddhism uses the same term.

There are traditions of [[contemplation?]] and [[discursive_meditation?]] in the West.

The best way to understand meditation of any form is to try it: How to Meditate