1. a part or organ resembling a barb of a feather, a fin, or the like.
  2. a finlet.
Botany. a secondary pinna, one of the pinnately disposed divisions of a bipinnate leaf.
a metal plate with a small hole in it, used as a sight in a quadrant.

Origin of pinnule

1585–95; < Latin pinnula pinnula
Related formspin·nu·lar [pin-yuh-ler] /ˈpɪn yə lər/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for pinnule

Historical Examples of pinnule

  • The index reference for "Pinnule" should probably be 59, rather than 66, but was not changed.

  • Pinnule, a secondary division of a bipinnate or tripinnate leaf, 66.

  • Sporangia in oblong sori under a reflexed tooth of a pinnule; indusium broad; rachis dark and shining.

    The Fern Lover's Companion

    George Henry Tilton

  • The sori are placed on small veins which grow outwards from the midrib of the pinnule.

    How to Know the Ferns

    S. Leonard Bastin

  • They occur about midway between the central vein of the pinnule and the margin of the leaf.

    How to Know the Ferns

    S. Leonard Bastin

British Dictionary definitions for pinnule


pinnula (ˈpɪnjʊlə)

noun plural pinnules or pinnulae (ˈpɪnjʊˌliː)

any of the lobes of a leaflet of a pinnate compound leaf, which is itself pinnately divided
zoology any feather-like part, such as any of the arms of a sea lily
Derived Formspinnular, adjective

Word Origin for pinnule

C16: from Latin pinnula, diminutive of pinna feather
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

pinnule in Science



Any of the smaller leaflets into which each leaflet of a bipinnately compound leaf is subdivided. The leaves of many ferns are divided into pinnules.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.