An object is a thing.
Also known as
Lewis Carroll (Charles Lutwidge Dodgson), one of the first to consider such a basic abstraction, used the word thing.
Another word used in this context is entity.
- 1962: Bert Mendelson: Introduction to Topology ... (previous) ... (next): $\S 1.2$: Sets and Subsets
- 1965: Seth Warner: Modern Algebra ... (next): Chapter $1$: Algebraic Structures: $\S 1$: The Language of Set Theory
- 1975: T.S. Blyth: Set Theory and Abstract Algebra ... (previous) ... (next): $\S 1$
- 1977: William Warren Bartley, III: Lewis Carroll's Symbolic Logic
- 1993: Keith Devlin: The Joy of Sets: Fundamentals of Contemporary Set Theory (2nd ed.) ... (previous) ... (next): $\S 1.1$: What is a Set?