Wikipedia says some categorize avocadoes as drupes:

en.wikipedia.org/wiki/Berry_(botany)

Drupes have pits contained within a hard shell (I guess called an endocarp?).

Peach pits look like an almond inside of a walnut shell basically. Avocados just have a really large seed in direct contact with the buttery soft mesocarp.

I don’t know who decided to classify gourds, melons, and citrus fruits as berries, but I imagine they had mischief in mind…