adjective1. equal or interchangeable in value, quantity, significance, etc
2. having the same or a similar effect or meaning
3. mathematicsa. having a particular property in common; equal
b. (of two equations or inequalities) having the same set of solutions
c. (of two sets) having the same cardinal number
4. mathematics, logic (of two propositions) having an equivalence between them
noun5. something that is equivalent
6. short for equivalent weight