Seventh

Seventh is the ordinal form of the number seven, used to indicate position in a sequence or order. As a cardinal, seven is the integer between six and eight. In fractions, a seventh is one part of seven equal parts; the reciprocal of seven is written as 1/7 and equals approximately 0.142857… in a repeating decimal.

In music, the term seventh describes both a scale degree and an interval. The seventh scale degree is the note that is seven steps above the tonic; in a major scale this degree is often a leading tone. An interval of a seventh spans seven letter names and can be classified by its quality, such as major seventh (11 semitones), minor seventh (10 semitones), or diminished seventh (9 semitones, spelled as a seventh). Seventh chords stack a seventh above a triad, giving rise to major seventh, minor seventh, dominant seventh, half-diminished seventh, and diminished seventh varieties.

In astronomy, the seventh planet from the Sun is Uranus.

In calendars and culture, the seventh day of the week is defined differently by tradition: some systems designate Saturday as the seventh day, while others treat Sunday as the seventh or as the first day, depending on where the week starts.

Etymology notes that the word seventh derives from seven plus the English ordinal suffix, tracing back to Old English.