pen·nate 
(pĕnāt′)
(pĕnāt′)adj.
1. Having feathers or wings.
2. Having elongate, bilaterally symmetrical valves. Used of diatoms.
3. Resembling a feather. Used especially of a muscle whose fibers extend obliquely from a tendon.
[Latin pennātus, from penna, feather; see pet- in the Appendix of Indo-European roots.]