rhythm

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Movement or variation characterized by the regular recurrence or alternation of different quantities or conditions.
• noun The patterned, recurring alternations of contrasting elements of sound or speech.
• noun The patterning of musical sound, as by differences in the timing, duration, or stress of consecutive notes.
• noun A specific kind of such patterning.
• noun A group of instruments supplying the rhythm in a band.
• noun The pattern or flow of sound created by the arrangement of stressed and unstressed syllables in accentual verse or of long and short syllables in quantitative verse.
• noun The similar but less formal sequence of sounds in prose.
• noun A specific kind of metrical pattern or flow.
• noun The sense of temporal development created in a work of literature or a film by the arrangement of formal elements such as the length of scenes, the nature and amount of dialogue, or the repetition of motifs.
• noun A regular or harmonious pattern created by lines, forms, and colors in painting, sculpture, and other visual arts.
• noun The pattern of development produced in a literary or dramatic work by repetition of elements such as words, phrases, incidents, themes, images, and symbols.
• noun Procedure or routine characterized by regularly recurring elements, activities, or factors.

from The Century Dictionary.

• noun A rhythm produced by alternations of clang-tint—in the simplest case, by compound tones alike in duration, pitch, and energy, but different in tint (as proceeding from different instruments, or sung by different voices).
• noun In music: Same as duple rhythm.
• noun A rhythm with only two or three beats to the measure: opposed to compound rhythm or time. See compound measure.
• noun Movement in time, characterized by equality of measures and by alternation of tension (stress) and relaxation.
• noun In music: That characteristic of all composition which depends on the regular succession of relatively heavy and light accents, beats, or pulses; accentual structure in the abstract.
• noun A particular accentual pattern typical of all the measures of a given piece or movement.
• noun In metrics: Succession of times divisible into measures with theses and arses; metrical movement.
• noun A particular kind or variety of metrical movement, expressed by a succession of a particular kind or variety of feet: as, iambic rhythm; dactylic rhythm.
• noun A measure or foot.
• noun Verse, as opposed to prose. See rime.
• noun In physics and physiology, succession of alternate and opposite or correlative states.
• noun In the graphic and plastic arts, a proper relation and interdependence of parts with reference to each other and to an artistic whole.
• noun Synonyms Melody, Harmony, etc. See euphony.

from the GNU version of the Collaborative International Dictionary of English.

• noun In the widest sense, a dividing into short portions by a regular succession of motions, impulses, sounds, accents, etc., producing an agreeable effect, as in music poetry, the dance, or the like.
• noun (Mus.) Movement in musical time, with periodical recurrence of accent; the measured beat or pulse which marks the character and expression of the music; symmetry of movement and accent.
• noun A division of lines into short portions by a regular succession of arses and theses, or percussions and remissions of voice on words or syllables.
• noun The harmonious flow of vocal sounds.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The variation of strong and weak elements (such as duration, accent) of sounds, notably in speech or music, over time; a beat or meter.
• noun A specifically defined pattern of such variation.
• noun A flow, repetition or regularity.
• noun The tempo or speed of a beat, song or repetitive event.
• noun The musical instruments which provide rhythm (mainly; not or less melody) in a musical ensemble.
• noun A regular quantitative change in a variable (notably natural) process.
• noun Controlled repetition of a phrase, incident or other element as a stylistic figure in literature and other narrative arts; the effect it creates.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun 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)
• noun recurring at regular intervals
• noun the arrangement of spoken words alternating stressed and unstressed elements
• noun an interval during which a recurring sequence of events occurs
• noun the basic rhythmic unit in a piece of music