1. small leaflets or divisions of a compound leaf, especially in ferns
Usage: botanical
2. small fin-like appendages or projections on marine animals
Usage: zoological

Examples

• The fern’s pinnules were arranged in neat rows along each frond.
• Each pinnule on the compound leaf had its own distinct shape.
• The botanist examined the pinnules under a magnifying glass.
• Sea lilies have feathery pinnules that help them filter food from water.
• The fossil showed well-preserved pinnules from an ancient fern.
• Damaged pinnules on the plant indicated possible disease.