Internal means inside — the opposite of external. An interval is a gap between two points, in time, space or music. An internal investigation; a ten-minute interval. One is an adjective about location; the other is a noun about spacing.
The core difference
- internal — on or of the inside; within an organisation or body. Internal organs, an internal memo, internal affairs.
- interval — a gap between two things; a pause in a performance; in music, the distance between two notes. At regular intervals, the interval is twenty minutes, an interval of a fifth.
The tell
Internal ends in -al like its opposite external, and it describes. Interval ends in -val, from the Latin for a rampart — it is the space between two walls, and it names a gap. If you can put an or the in front and a length after it, it is an interval.
In use
- internal — The company opened an internal investigation. The patient had internal bleeding.
- interval — There will be a short interval after the first act. Check the readings at hourly intervals.
Common slips
- an interval investigation → an internal investigation
- a ten-minute internal → a ten-minute interval
Internal is inside; interval is in between.
Where the words come from
Internal is from Latin internus, "inward", from inter "within". Interval is from Latin intervallum, "the space between ramparts" — inter "between" + vallum "wall", the same vallum that gives us wall. The musical and theatrical senses are both that gap.
Frequently asked questions
What is an interval in music?
The distance in pitch between two notes — a third, a fifth, an octave.
Is it "intermission" or "interval"?
Both — interval is the usual British word for the break in a performance, intermission the American.
What is the opposite of internal?
External. Interval has no opposite; it is a gap.