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in·ter·val

(ĭntər-vəl)

1. A space between objects, points, or units, especially when making uniform amounts of separation: We set up hurdles at intervals of 15 yards around the track.

2. An amount of time between events, especially of uniform duration separating events in a series: We ran laps at 30-second intervals.

3. A segment of an athletic workout in which an athlete runs, swims, or does other exercise over a series of predetermined distances at regular time increments with intermittent rests.

4. Mathematics

a. A set of numbers consisting of all the numbers between a pair of given numbers along with either, both, or none of the endpoints.

b. A closed interval.

c. An open interval.

d. A half-open interval.

e. A line segment representing the set of numbers in an interval.

5. Chiefly British An intermission, as between acts of a play.

6. Music The difference, usually expressed in the number of steps, between two pitches.

Idiom:

at intervals

In a series separated by space or time: trees planted at intervals; coughing at intervals.

[Middle English intervalle, from Old French, from Latin intervallum : inter-, inter- + vallum, rampart.]

in′ter·valic, in′ter·vallic (-vălĭk) adj.

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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