Terza Rima:
From Ann Gasser's "Awakening The Poet Within", a terza rima is "a form of chain verse in iambi rhythm usually written in iambic pentameter, though other meters can be found. The terza rima is not stanzic, it is written in groups of three lines (although some poets divide these groups with white space between, so they have the same appearance as stanzas.) The form ends with a couplet. (A 14 line terza rima is called a terza rima sonnet.)"

The terza rima uses a rhyme scheme (a, b, a, b, c, b, c, d, c, d, e, d, e) with the pattern repeating in the same manner for the length of the poem, with no limit on the length. Ann notes that the ending couplet is rhymed and uses the middle rhyme from the last group of three lines.

Terza Rima
rhyme scheme
Terza Rima Sonnet
rhyme scheme
"example"
aa(mate)
bb(fall)
aa(late)
bb(ball)
cc(right)
bb(call)
cc(might)
dd(star)
cc(sight)
dd(far)
ee(care)
dd(bar)
ee(hare)
fe(flair)
e
f
g
f
g
g

Another source ["The Study and Writing of Poetry" by Wauneta Hackleman revised by Amy Jo Zook], does not mention the use of a couplet as being necessary to end the poem. Hackleman makes note that the couplet is needed when writing a terza rima sonnet.

EXERCISE:
Compose a terza rima. Limit the length to 20 lines (14 lines if composing a terza rima sonnet). Use a rhyming couplet to end the poem.