Real Dictionary

impressionist
countable noun: An Impressionist is an artist who painted in the style of Impressionism.
countable noun: An impressionist is an entertainer who does amusing imitations of well-known people.

impressionist in American English
a painter, writer, or composer who practices impressionism
of impressionism or impressionists
adjective: of, pertaining to, or characteristic of Impressionism
noun: a person who follows or adheres to the theories, methods, and practices of impressionism, esp. in the fields of painting, music, or literature

impressionist in British English
adjective: denoting, of, or relating to impressionism or the exponents of this style
noun: any of the French painters of the late 19th century who were exponents of impressionism