An instrument is a concrete or abstract tool intended for a purpose other than mechanical work, in particular a refined one.
Musical instruments are devices designed to produce music, frequently by plucking or striking a string or bell or drum surface, or by forcing air to resonate (see wind instruments).
... Catechism[?] and the Second Helvetic Confession[?] as a definition of their teaching, together the Ecumenical creeds of the Christian Church: Athanasian Creed, Nicene ...