- Biology. having radial symmetry.
- Botany. (of certain flowers, as the buttercup) divisible vertically into similar halves by each of a number of planes passing through the axis.
- botany (esp of a flower) having radial symmetry, as buttercupsSee also zygomorphic
- Relating to a flower that can be divided into equal halves along any diameter; radially symmetrical. The flowers of the rose and tulip are actinomorphic. Compare zygomorphic.