- Interval (music): Add brief definition or description
- Interval (order): The elements which lie between two given members of a partially ordered set.
- Confidence interval: the range of a random variable, such as the mean of a sample, that — with a specified probability — contains the true value for the population.
- QT interval: In cardiology and the electrocardiogram, the time between the start of the Q wave and the end of the T wave.
- : A subset of the real line consisting of all numbers between (but not including) two given numbers.
- : A subset of the real line consisting of all numbers between (and including) two given numbers.