##### Wiktionary

**open interval**

n. (context mathematics English) an interval in the real number line which does not contain its supremum and infimum. If specified by a pair of real numbers, then it consists of all the points on the real line whose values lie strictly between those two real numbers.

##### WordNet

**open interval**

n. an interval that does not include its endpoints [syn: unbounded interval] [ant: closed interval]