chamber concerto; concerto di camera
A concerto for a small ensemble, typical of the Baroque period. The Italian term 'concerto di camera' is also used in musicology.
Bach's chamber concertos are written for small ensembles.
A general concerto, often for a solo instrument with orchestra. 室内協奏曲 specifically denotes a chamber concerto for a smaller group.
Compound of 室内 (shitsunai, 'indoor' or 'chamber') and 協奏曲 (kyōsōkyoku, 'concerto'). The term is a direct translation of the Italian 'concerto da camera' or English 'chamber concerto'.