Metre (British) or Meter (American) is the regulated patterning of speech-rhythm (see prosody) so as to produce a partial resemblance or equivalence between successive segments of verse, usually called lines.
Metre has traditionally been a defining feature of verse (but see free verse). In English the regulated features are known as beats. In addition other prosodic features, such as the number of syllables, may also be constrained.
Groves, Peter Lewis. "Metre / Meter". The Literary Encyclopedia. First published 23 June 2004
[http://www.litencyc.com/php/stopics.php?rec=true&UID=1217, accessed 22 January 2017.]