n. pl. mo·dal·i·ties
1. The fact, state, or quality of being modal.
2. A tendency to conform to a general pattern or belong to a particular group or category.
3. Logic The classification of propositions on the basis of whether they assert or deny the possibility, impossibility, contingency, or necessity of their content. Also called mode.
4. modalities The ceremonial forms, protocols, or conditions that surround formal agreements or negotiations: "[He] grew so enthusiastic about our prospects that he began to speculate on the modalities of signing" (Henry A. Kissinger).
5. Medicine A therapeutic method or agent, such as surgery, chemotherapy, or electrotherapy, that involves the physical treatment of a disorder.
6. Physiology Any of the various types of sensation, such as vision or hearing.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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.