• synonyms


[grey-nuh m]
noun, plural gra·na [grey-nuh] /ˈgreɪ nə/.
  1. (in prescriptions) a grain.
  2. Botany. one of the structural units of a chloroplast in vascular plants, consisting of layers of thylakoids.
Show More

Origin of granum

From Latin
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for granum

Historical Examples of granum

  • The Spanish name grana, confounded with granum, may have given rise to this contest.

    Curious Facts in the History of Insects; Including Spiders and Scorpions.

    Frank Cowan

granum in Science


Plural grana (grā)
  1. A stacked membranous structure within the chloroplasts of plants and green algae that contains the chlorophyll and is the site of the light reactions of photosynthesis. The saclike membranes that make up grana are known as thylakoids. See more at chloroplast.
Show More
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.