Physics Terminology For Instability

noun a word (other than a pronoun) used to identify any of a class of people, places, or things

adverb a word or phrase that modifies or qualifies an adjective, verb, or other adverb

preposition a word governing, and usually preceding, a noun or pronoun and expressing a relation to another word or element in the clause

• The constant changes in the stock market have left investors on edge.
• I've been on edge ever since I heard about the upcoming exam.
• She's been on edge all day because of the argument with her friend.
• The suspenseful movie had me on edge the entire time.