Definition of pinnate in US English:



  • 1(of a compound leaf) having leaflets arranged on either side of the stem, typically in pairs opposite each other.

    • ‘In 1794, Moench named A. tuberosa and described it as having tuberous roots, unevenly pinnate leaflets, and purple flowers in lateral racemes.’
    • ‘Immatures have a weakly developed taproot, and have pinnate compound leaves with two or three leaflets.’
    • ‘Green stems are interconnected by sensitive petioles and bear pinnate leaves.’
    • ‘All of these foliage forms are planate pinnate fronds, frequently with open venation.’
    • ‘It has pinnate leaves and racemes of lilac pink flowers, which are slightly fragrant.’
    1. 1.1Zoology (especially of an invertebrate animal) having branches, tentacles, etc., on each side of an axis, like the vanes of a feather.
      • ‘The colonies are erect, typically delicate; reticulate (net-like) or pinnate (fern-like).’
      • ‘Arrangement of septa in earliest stages pinnate in all quadrants.’
      • ‘The microsporophyll of Lepidopteris has been reconstructed as a pinnate axis with short branches bearing clusters of small elongate pollen sacs fused at the base.’


Early 18th century: from Latin pinnatus ‘feathered’, from pinna, penna (see pinna).