Chaucerian stanza is another name for rhyme royal: a seven-line stanza written in iambic pentameter with the rhyme scheme ababbcc. Chaucer used this stanza form in some of his poems, and later writers adopted it for dignified, reflective verse.
See rhyme royal.
Example
The winter dusk leaned blue against the pane,
The hearth gave off a low and steady glow;
Outside, the wind went wandering through the lane,
And made the bare black branches nod and bow.
I set my cup aside and watched it snow,
Then wrote one quiet line and let it stay,
A small bright ember against the fading day.