Pianist

google

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mid 19th century: from French pianiste, from piano (see piano1).

wiktionary

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From French pianiste, from Italian pianista. Analyzable as piano +‎ -ist.

etymonline

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pianist (n.)

"a performer on the pianoforte," 1822, from French pianiste, from Italian pianista; see piano + -ist. Earlier in English in the French form, pianiste (1816).