interval /inˈtər-vəl/

1. Time or space between
2. A break between acts of a play, parts of a sports match, etc
3. Difference of pitch between any two musical tones (music)
4. A set of real numbers or points between two given numbers or points (mathematics)

intervallic /-valˈik/ adjective

intervalomˈeter noun (photography)

A device for operating the shutter at set intervals

interval training noun

Alternate fast and slow running at measured intervals in one session, done as training work for marathons and other long-distance races

at intervals

1. Periodically
2. With prescribed spaces between

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