noun
A person who composes music; a standard, neutral term.
彼は有名な作曲家です。
He is a famous composer.
この曲の作曲家は誰ですか。
Who is the composer of this piece?
作詞家 writes lyrics, while 作曲家 writes the music.
Compound of 作曲 (composition) + 家 (person who does that activity).