"Approximate" is an adjective and a verb that is used to describe something that is close to, but not exactly, a specific value, quantity, or quality. It means to estimate or come close to a particular value or characteristic without being precise or exact. When something is approximate, it is an educated guess or a rough measurement rather than an exact or precise one.
For example, if you say, "The approximate cost of the meal was $20," it means that the cost of the meal was close to $20 but may have been slightly more or less. It is not an exact figure.
In mathematics and science, approximation is a technique used to simplify complex problems by using simpler, easier-to-work-with values that are close enough to the real values to be useful for practical purposes.