actine
1 of 2noun
ac·tine
ˈak-ˌtīn,
-tən
plural -s
: a star-shaped spicule (as of a sponge)
-actine
2 of 2adjective combining form
¦ak-(ˌ)tīn,
-tən
: having (such or so many) rays
discoactine
pentactine
—especially in terms applied to sponge spicules 
Word History
Etymology
Noun
Greek aktin-, aktis ray
Adjective combining form
Greek aktin-, aktis
First Known Use
Noun
1887, in the meaning defined above