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. [1]
| 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. | 
 "Exposure", by Wilfred Owen, [3]  also has an example of enclosed rhyme. Each of the eight stanzas have the ABBA half rhyming sequence:
| Our brains ache in the merciless iced east winds that knive us ... | ||
| Wearied we keep awake because the night is silent ... | ||
| Low, drooping flares confuse our memories of the salient ... | ||
| Worried by silence, sentries whisper, curious, nervous, | ||
| But nothing happens. |