An idiom (, "special property", from , "special feature, special phrasing, a peculiarity", f. , "one’s own") is a phrase or a fixed expression that has a figurative, or sometimes literal, meaning. An idiom's figurative meaning is different from the literal meaning. There are thousands of idioms, and they occur frequently in all languages. It is estimated that there are at least twenty-five thousand idiomatic expressions in the English language. Idioms fall into the category of formulaic language.

The Java Unified Expression Language is a special purpose programming language mostly used in Java web applications for embedding expressions into web pages. The Java specification writers and expert groups of the Java web-tier technologies have worked on a unified expression language which was first included in the JSP 2.1 specification (JSR-245), and later specified by itself in JSR-341, part of Java EE 7.