From Poetry Wiki
Enclosed rhyme (or enclosing rhyme) is the rhyme scheme "abba" (that is, where the first and fourth lines, and the second and third lines rhyme). Enclosed-rhyme quatrains are used in introverted quatrains, as in the first two stanzas of Petrarchan sonnets.
- How soon hath Time, the subtle thief of youth,
- Stolen on his wing my three and twentieth year!
- My hasting days fly on with full career,
- But my late spring no bud or blossom shew'th.
- (From John Milton's "On His Being Arrived to the Age of Twenty-Three")