I second that suggestion. I don't know if there's a specific name, although I doubt it, but "stretched tetrahedron" is both precise, evocative, and most accurately conveys all of the likely properties. (I was going to say 'elongated', but apparently that means something else. In theory you should specify along what axis it is stretched, but I think it's fairly clear: the only other good choice is to stretch it perpendicular to one of the faces, and that's plainly called a "tall" tetrahedron :))