(mathematics, logic, of a relationship between two sets) having the property that many elements of one set may be assigned by the relationship to one element in the other set, and that a given element in the first set can be assigned by only one member of the second set.

(mathematics, of a function) Having the property that the same argument may yield multiple values, but different arguments never yield the same value.

That one has chosen, or wishes to choose.

plural of bolt-on

One-upmanship among women.

The ideology that all of the countries of the world are essentially similar and could interoperate without conflict.

(finance) Being or relating to a kind of exotic option that pays out if an asset reaches or passes a certain price at any point during the relevant period.

plural of hard on

(slang) To fart.

plural of one-of