inter- ‘between’ + vallum ‘rampart’

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1. an intervening time or space:

«…間の» (時間･空間などの)間隔

e.g. after his departure, there was an interval of many years without any meetings

e.g. the intervals between meals were very short.

a component of activity in interval training:

e.g. use one day a week for short, sprint intervals.

2. a pause or break in activity:

合間, 休止期間 «between»

e.g. an interval of mourning.

British an intermission separating parts of a theatrical or musical performance.

｟主に英｠ (演劇･コンサートなどの)休憩時間, 幕間（まくあい）(｟主に米｠ intermission)

a break between the parts of an athletic contest:

(程度の)隔たり

e.g. United led 3-0 at the interval.

3. a space between two things; a gap.

4. the difference in pitch between two musical sounds.

〘楽〙 音程

1. with time between; not continuously:

e.g. the light flashed at intervals.

2. with spaces between:

e.g. the path is marked with rocks at intervals.

intervallic |ˌin(t)ərˈvalik| adjective

Middle English: from Old French entrevalle, based on Latin intervallum ‘space between ramparts, interval’, from inter- ‘between’ + vallum ‘rampart’.