actinal adjective2 •Pertaining to the side or surface around the mouth in an animal that has radial symmetry such as a starfish.The so-called mouth is always placed at one of these poles, and from it radiate the most prominent organs, in consequence of which I have called this side of the body the oral or actinal area ... — 1857 •Pertaining to the axis of rotational symmetry in radiate animals.[Professor Agassiz] gives the names of two axes of the animals; that around which the motion of the animal occurs is the actinal axis ... — 1861
