- any of the smallest divisions of a leaf which is doubly compound, esp. in ferns
- any of the lateral branches of the arm of a crinoid
Origin of pinnuleModern Latin pinnula from L, diminutive of pinna, wing, feather: see pen
nounpl. pin·nules, also pin·nu·lae
- Botany One of the secondary divisions of a binnately compound leaf.
- Zoology A small featherlike part or subdivision of an appendage, especially one of the small branches on the arm of a crinoid.
Origin of pinnuleLatin pinnula diminutive of pinna feather ; see pet- in Indo-European roots.