Noun: Classy breasts viewed from the side. Similar to sideboob, but of the highest quality. Can be clothed or un-clothed, but the outline of the breast must be clearly defined.
The finest source of this phenomenon is sidebreast.com
See also: sideboob
Her boobs look good enough to qualify as sidebreast. Yeah, did you see her sidebreast when she leaned over to get that pen?