Dictionary.net

• in-t[.e]r-r[=a]'di-al, adj. situated between the radii or rays.--adv. INTERR[=A]'DIALLY.--n. INTERR[=A]'DIUS, an interradial part, esp. of a hydrozoan.

1908 - Chambers's Twentieth Century Dictionary of the English Language
By Thomas Davidson