Plural of fourth; fractions or intervals representing 1/4 of something or four equal parts, or positions ranked as number four.
From 'fourth' (Old English 'feortha', ordinal from 'feower' meaning four) with plural '-s' ending.
In music, a perfect fourth (like C to F) was considered dissonant and banned from medieval church music, yet today it's one of the most harmonic and pleasing intervals to our ears.
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