in alliterative verse, a group of typically five rhymed lines following a section of unrhymed lines, often at the end of a strophe. The bob is the first line in the group and is shorter than the rest; the wheel is the quatrain that follows the bob.
BOB AND WHEEL
Meaning of BOB AND WHEEL in English
Britannica English vocabulary. Английский словарь Британика. 2012