Any of several cytoplasmic organelles, such as chloroplasts, that contain genetic material, have a double membrane, and are often pigmented. Plastids are found in plants, algae, and certain other eukaryotic organisms and have various physiological functions, such as the synthesis and storage of food.
[From Greek plastis, plastid-, feminine of plastēs, molder, from plastos, molded; see PLASTIC.]
plas·tidi·al (plăs-tĭdē-əl) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.