The term "left flat" refers to a position where flatness is retained and objects or surfaces are situated towards the left side. Antonyms for "left flat" include right-angled or tilted, where objects or surfaces are situated at a certain angle to the right side. Another antonym is arched, where the surface is curved or rounded instead of flat. Elevated or raised may also be considered as antonyms for left flat, where objects or surfaces are positioned at a higher level. Finally, slanted or sloping is also an antonym for left flat, where an object or surface is positioned at a certain angle or gradient.