Cadence is a term borrowed from music, where it refers to the use of a group of notes or chords used to end a piece of music or a phrase within it. As it can also be used to refer to the audible features of speech - a statement slowing and falling in pitch as it ends, for example, or the pause that a comma demands - it has been taken up by poets to refer to the pitch and rhythm of words within a poem. Unlike discussions of metre, which refer to the beat underlying what is said, cadence attends to actual variations.
For example, Ian McMillan's 'For Me', a poem about not having to rhyme, makes three ridiculous arguments that use the same cadences; this achieves the effects of linking the stanzas by sound, without using rhyme. In Michael Longley's 'The Ice-Cream Man', there is a recurring metre ticking away under the whole poem, but a line that contains a narrative sentence, such as "and you bought carnations to lay outside his shop", carries a different cadence from one containing a list, like "Meadowsweet, tway blade, crowfoot, ling, angelica". This is one way of keeping a regular metre from becoming dull with repetition, and also has the effect of binding the two list cadences, of flowers and flavours, a little closer in the ear.