Definition of plant clarifies included items and specific exclusions for income tax depreciation and allowance treatment. Definition of plant in the Income-tax Act includes movable and operational assets such as ships, vehicles, books, scientific apparatus and surgical equipment when used for business or profession, and excludes tea bushes, livestock, buildings and furniture and fittings; a related provision for section 44BB likewise includes ships, aircraft, vehicles, drilling units, scientific apparatus and equipment used in the specified business, thereby determining asset classification for capital allowance and depreciation treatment.