1. An abnormal membranous sac in the body containing a gaseous, liquid, or semisolid substance.
2. A sac or vesicle in the body.
3. Biology A small capsulelike sac that encloses certain organisms in their dormant or larval stage.
4. Botany A thick-walled resting spore, as in certain algae or fungi.
[New Latin cystis, from Greek kustis, bladder; see kwes- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 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.