adjective.
Having flower parts, such as petals, sepals, and stamens, in sets of five.
The Century Dictionary and Cyclopedia
Five-parted; five-jointed; composed or consisting of five parts or five sets of similar parts.
the GNU version of the Collaborative International Dictionary of English
adjective.
Divided into, or consisting of, five parts; also, arranged in sets, with five parts in each set, as a flower with five sepals, five petals, five, or twice five, stamens, and five pistils.