"a performer on the pianoforte," 1822, from French pianiste, from Italian pianista; see piano + -ist. Earlier in English in the French form, pianiste (1816).
Entries linking to pianist
piano n.
"percussion musical instrument in which tones are produced by blows of hammers upon stretched strings, the hammers being operated from a keyboard," 1803, from French piano (18c.), Italian piano, shortened forms of pianoforte (q.v.).
Essentially, the pianoforte is a large dulcimer with a keyboard ; but historically it replaced the clavichord and harpsichord, which were keyboard-instruments more akin to the harp than to the dulcimer. [Century Dictionary]
Piano wire "kind of strong steel wire used for strings of pianos," is attested from 1831. Piano-case "wooden box enclosing the mechanism of a piano" is by 1844.
-ist
word-forming element meaning "one who does or makes," also used to indicate adherence to a certain doctrine or custom, from French -iste and directly from Latin -ista (source also of Spanish, Portuguese, Italian -ista), from Greek agent-noun ending -istes, which is from -is-, ending of the stem of verbs in -izein, + agential suffix -tes.
Variant -ister (as in chorister, barrister) is from Old French -istre, on false analogy of ministre. Variant -ista is from Spanish, popularized in American English 1970s by names of Latin-American revolutionary movements.