Definitions

1. noun

a set of operators following the operands in a mathematical expression

“The postfix notation of the expression 2 + 3 is 2 3 +.”

2. verb

to add a suffix to something, especially to indicate a grammatical function

“The word ‘running’ is the postfix of the verb ‘run’.”

3. noun

a suffix attached to a word to indicate its grammatical function

“The postfix -ing indicates a present participle.”