Botanically, the term describes once-divided leaves comprising leaflets that are arranged on both sides of a petiole, a feature displayed by many palmss (notable the feather palms) and most cycads. Pinnate plants are sometimes known as "feather-leaved". Some species of fern also sport pinnate fronds, although others can be bipinnate, tripinnate or simple.
The leaflets that comprise a pinnate (or bipannate) leaf are known as pinnae or pinnules.
See also: paripinnate, imparipinnate, bipinnate, tripinnate, palmate, costapalmate, simple