Pennate is used to mean "winged", "feathered" or simply "shaped like a wing". The latter definition is sometimes used to describe plant leaf morphology (see lanceolate).

Pennate diatoms are bilaterally symmetrical, and belong to the order Pennales

Pennales

Order Pennales is a traditional subdivision of the heterokont algae known as diatoms. The order is named for the shape of the cell walls of pennate diatoms, which are elongated in valve view. The valves may be linear or oval in shape, and usually bear bilaterally symmetrical ornamental patterns...

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The terms unipennate and bipennate are used anatomically in reference to feather-shaped muscles, such as extensor digitorum longus.