☞ -act, -actine

-act
I. \ˌakt\ adjective combining form
Etymology: Greek aktis ray — more at actin-
: having (such or so many) rays
 < polyact >
 < tetract >
— in terms applied to sponge spicules
II. noun combining form
(-s)
: one having (such or so many) rays
 < hexact >
 < triact >
— in names of sponge spicules