What does postfix mean?
A postfix is something placed after another element. In language, it means an affix added to the end of a word, such as “-ly,” “-ment,” or “-able,” and is closely related to the more familiar term “suffix.” The word is also used in computing and mathematics for an operator or expression placed after its operand: postfix increment, for example, writes the operation after the variable as in “count++.” This contrasts with prefix notation, where the operator comes first, and with infix notation, where it appears between operands, as in “2 + 3.” Although “suffix” is usually preferred in everyday linguistic discussion, “postfix” remains valuable because it precisely describes the position of an element and is standard terminology in programming and formal notation. It can therefore describe both a word-forming element and the arrangement of operations in symbolic systems.
An affix added to the end of a word.
"The English word “hopeful” contains the postfix “-ful.”"
In general linguistics, “suffix” is more usual; “postfix” is especially common in technical descriptions of computing and mathematical notation.
An operator or expression placed after its operand, especially in computing and mathematical notation.
"The program evaluates the postfix before applying the next operation."
This technical sense contrasts with prefix notation, where the operator precedes the operand.
The plural is formed by adding “-es”.
"The compiler adds several postfixes to the expression during optimization."
In programming, postfix puts the operator after the operand, as in “5++” rather than “++5.”
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does postfix come from?
“Postfix” combines the Latin “post,” meaning “after,” with “fix,” from the Latin root meaning “to fasten.” The resulting term literally refers to something fixed or attached after another element. It belongs to a family of English terms formed from Latin roots describing word-element position, including “prefix,” “infix,” “suffix,” and the broader “affix.”
Related word forms
How postfix is actually used
In general linguistics, “suffix” is the usual term. “Postfix” is especially common in computing, mathematics, and discussions of notation systems.
Easily confused with postfix
A suffix is specifically an affix added to the end of a word, while “postfix” is a more technical term that is also widely used for end-placed operators in computing and mathematics.