1Belief in or advocacy of taking action; activism.
2Art. Also with capital initial. An artistic movement emphasizing the physical act or process of creation over the finished work; specifically (in later use) = Viennese Actionism.
Origin
Late 19th century (in an earlier sense). From action + -ism.
Definition of actionism in US English:
actionism
noun
1Belief in or advocacy of taking action; activism.
2Art. Also with capital initial. An artistic movement emphasizing the physical act or process of creation over the finished work; specifically (in later use) = Viennese Actionism.
Origin
Late 19th century (in an earlier sense). From action + -ism.