The term "leaves flat" can be easily defined as something that has no texture or contour. Some antonyms for this phrase could be "textured," "patterned," "contoured," "curved," "protruding," or "bumpy." If we're talking about a physical object, it could be a smooth, flat sheet of paper versus a crumpled, creased, or embossed one. In art, a "leaves flat" technique would produce a two-dimensional image with little shading or depth, whereas a three-dimensional sculpture could be full of twists, turns, and irregularities. Ultimately, the opposite of "leaves flat" would be something with more visual interest and complexity, whether that's physical or artistic.