Though there are some who claim that a Tercet is any three-lined verse, it’s actually a poetry form with Italian roots. The classic form of a Tercet is a three-lined poetic stanza in which the first and third lines rhyme and the second line is a blank (unrhymed) line.
Today, we call this rhymed form an enclosed Ttercet because the two rhymed lines enclose the blank line. An even more stringent form of the Tercet is the Sicilian Tercet. The Sicilian Tercet incorporates the enclosed form, but also requires that the poet write in iambic pentameter.
The Tercet is rarely a complete poem in itself. Instead, poets write multiple stanzas of Tercets to create longer works. The best example of this is Dante’s Divine Comedy.
The Triad (Welsh and Irish) is a form composed of three Tercets. Welsh versions of the Arthurian legends make heavy use of this form.
The Triad is one of the lesser known poetry forms, but it is an enjoyable outlet for expression. You can add as much challenge as you wish. You can simply write in three-line stanzas or you can use iambic pentameter and enclosed Tercets if you wish to increase the writing challenge.
Spirit of Summer
The wind sloughs softly through the trees at dusk
Chasing the lingering rays of the sun
Filling the air with the garden’s sweet musk
Soon stars will appear and spirits will rise
To caper and dance beneath the moon’s light
To celebrate life and all it implies
Too soon the stars fade and vanish from sight
The moon runs its course and sets in the west
The revels are done until the next night