This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. The theory and practice of abstract art.

n. a representation having no reference to concrete objects or specific examples

n. an abstract genre of art; artistic content depends on internal form rather than pictorial representation

"The other side gallery, for figurative works made while abstractionism and later -isms reigned in the 1940s through the '80s, falls apart even more quickly."

internal representation    mental representation    representation