associative array
A collection of key/value (or name/value) pairs such that each possible key appears at most once in the collection. In JavaScript (and JSON), all objects behave as associative arrays with string-valued keys. In Python and .NET, associative arrays are called dictionaries. In Java and Go, they are called maps. In Ruby, they are called hashes. See also: Wikipedia’s articles for Associative array and Comparison of programming languages (associative array)