Outside \Out"side`\, a. 1. Of or pertaining to the outside; external; exterior; superficial. 2. Reaching the extreme or farthest limit, as to extent, quantity, etc.; as, an outside estimate. [Colloq.] {Outside finish} (Arch.), a term for the minor parts, as corner boards, hanging stiles, etc., required to complete the exterior of a wooden building; -- rare in masonry.