Of, pertaining to, or in the style of expressionism(adjective)
A painter who paints in this style(noun)
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Use "expressionist" in a sentence
"Boesch's methodology has often been described as expressionist, though in this instance he's less overtly declamatory than you might expect, singing the work as much off the lines as the text."
"In a general sense, painters such as Matthias Grünewald and El Greco can be called expressionist, though in practice, the term is applied mainly to 20th century works."
"Rummaging through an old art-history text, I came across the opinion that Smith (1912-80) was too "expressionist" to be considered a doctrinaire Minimalist."