What is AC actually?
AC does not have a precise meaning, its meaning can be context dependent. It's probably better to identify various waveforms and ask whether they could be called AC.

A sinewave waveform with a zero average would certainly count as AC.

A square, triangle or any other waveshape with a zero average would also count as AC.

If any of these waveforms had a small non-zero average, they could be described as AC with a small DC component.

Generally with AC, the 'alternating' part of the description suggests (but it's only as weak as suggests) that the waveform reverses polarity from time to time. If one of the waveforms above had a large DC average, such that it didn't reverse, then it could be described as fluctuating DC, or DC with ripple (as Michael K points out), or could be called AC on top of DC, or AC with a large DC component. All would be correct, or at least, none of them are wrong.

In all cases, if it really matters what the waveform is, then describe the waveform voltage as a function of time, don't get hung up on how different people try to name it. If it's in an exam or class assignment, then memorise what your tutor expects to see (it will be in their notes), and just reproduce that for the marks.