A small enclosed structure or cavity, especially:
a. Cytology A membrane-bound structure within a cell in which materials such as enzymes are transported or stored.
b. Anatomy A sac or cyst, especially one containing fluid.
c. Medicine A blister of the skin.
d. Geology A cavity formed in volcanic rock by entrapment of a gas bubble during solidification.
[Middle English, from Old French vesicule, from Latin vēsīcula, diminutive of vēsīca, bladder, blister.]
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.