Noun
1. the basic rhythmic unit in a piece of music;
"the piece has a fast rhythm""the conductor set the beat"2. recurring at regular intervals
3. an interval during which a recurring sequence of events occurs;
"the neverending cycle of the seasons"4. the arrangement of spoken words alternating stressed and unstressed elements;
"the rhythm of Frost's poetry"5. natural family planning in which ovulation is assumed to occur 14 days before the onset of a period (the fertile period would be assumed to extend from day 10 through day 18 of her cycle)