twice-divided in a pinnate structure; generally on ferns (see pictorial glossary)
Having two rows of lateral branches, appendages, or other parts along an axis which are themselves again divided into two rows along an axis
A pinna with free pinules (i e, When a pinna is subdivided into leaflets that are free to the pinna rachis)
refering to a leaf: doubly pinnately compound, the leaf being pinnately divided into pinnae which are divided themselves into leaflets The leaves of Jacaranda mimosifolia is bipinnate