saxophone

Borrowed from French saxophone, formed from the surname of its inventor Adolphe Sax (1814–1894) plus a connecting -o- and -phone, meaning 'something that makes a sound,' from Ancient Greek phōnḗ ('sound, voice').

The facts given don't describe any shift in meaning — the word has named this brass-bodied instrument since it was coined for Sax's invention.

The surname Sax is itself a variant of German Sachs, meaning 'Saxon,' linking the instrument's name back to an old ethnic name before it ever meant music.