pennate

adjective

pen·​nate ˈpe-ˌnāt 

: of, relating to, or being usually elongate bilaterally symmetrical diatoms of an order (Pennales) having a raphe or a similar structure

Word History

Etymology

irregular from New Latin Pennales

First Known Use

1938, in the meaning defined above

Medical Definition

pennate

adjective

pen·​nate ˈpen-ˌāt 

: having a structure like that of a feather

especially : being a muscle in which fibers extend obliquely from either side of a central tendon