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So "gravity waves" are what we commonly call "waves"?

To be fair, both are 'waves' of some sort.

But, yeah, gravity waves are closer to the common understanding of the word 'waves'.

The current understanding of waves on a liquid surface is attributed to a clear boundary between two fluids with a density difference and a velocity gradient. Gravity plays no role in this.

Kelvin-Helmholtz instability: https://en.wikipedia.org/wiki/Kelvin%E2%80%93Helmholtz_insta...

Two fluids with a density difference and a velocity gradient usually have a common force acting upon them, e.g. gravity, which enforces so-said interface. Perturbations to the average interface are restored via this force, and these perturbations are called gravity waves.

KH Instabilities give rise to gravity waves.

Big water waves are gravity waves, but ripples are capillary waves, I think.

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