Vowel harmony plays an important role in the phonology of certain languages.

I learned how to calculate the harmonic mean in math class.

That painting is incongruous with the room's decoration.

There was discord between them.

He is an expert in harmonic analysis.

He is a perfectionist, and his approach to work is very strict.

This programming language is said to be Turing complete.

His performance was perfect and without blemish.

In mathematics, a perfect number refers to a number where the sum of its divisors, excluding the number itself, equals the number.

This fish is completely farmed, and no capture is done in the natural environment.