non-modal

adjective

1. of or relating to mode, manner, or form.
2. Music.
   1. pertaining to mode, as distinguished from key.
   2. based on a scale other than major or minor.
3. Also single modal. Transportation. pertaining to or suitable for transportation involving only one form of a carrier, as truck, rail, or ship.Compare bimodal(def 3), intermodal.
4. Grammar. noting or pertaining to mood.
5. Philosophy. pertaining to a mode of a thing, as distinguished from one of its basic attributes or from its substance or matter.
6. Logic. exhibiting or expressing some phase of modality.

noun

7. modal auxiliary.

adjective

1. of, relating to, or characteristic of mode or manner
2. grammar (of a verb form or auxiliary verb) expressing a distinction of mood, such as that between possibility and actuality. The modal auxiliaries in English include can, could, may, must, need, ought, shall, should, will, and would
3. philosophy logic
   1. qualifying or expressing a qualification of the truth of some statement, for example, as necessary or contingent
   2. relating to analogous qualifications such as that of rules as obligatory or permissive
4. metaphysics of or relating to the form of a thing as opposed to its attributes, substance, etc
5. music of or relating to a mode
6. of or relating to a statistical mode

adj.1560s, term in logic, from Middle French modal and directly from Medieval Latin modalis “of or pertaining to a mode,” from Latin modus “measure, manner, mode” (see mode (n.1)). Musical sense is from 1590s.