Reason: It's just a different type of cleavage.

I support.

I disagree. When I hear "cleavage," I specifically think of the cleft between breasts, not the bottom edge or underside of a breast. That's really why it's called "cleavage," because it's a cleft, i.e. "a deep division between two parts of the body." So the buttcrack is a cleft, the bit between tits is a cleft, but...well shit, maybe it is one. Goddamnit, how do I do this? I go in convinced of one thing, then argue myself onto the other side.

Ok. So while I agree that it could in fact be considered a type of cleavage, I still think it shouldn't be implied, just because "cleavage" connotes boob-trench. Otherwise we'd have to put cleavage on every image with an asscrack, and that just seems unnecessary.

RedOctober spoke

What he said. Plus, there are those that specifically look for underboobs and don't really care for cleaveage. They are really two different things.

Example of under boob with cleavage: post #166064

Example of under boob, no cleavage: post #217716

Example of no under boob, and cleavage: post #212724

As Red mentioned, you can have both, but you can have either as well
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On a related note, there seems to be a lot of posts tagged with under boob, though they depict a side boob shot instead (post #155840,post #214880)

Strother said:
Plus, there are those that specifically look for underboobs and don't really care for cleaveage

This would be unaffected by an implication.

That said, I don't think an implication would be helpful here, for reasons outlined above.