A circular chord progression in a temperament, which can only be executed when the tuning allows every adjacent pair of chords in the progression to have at least one common-tone, and the chord progression features a vapro of that temperament.
The most familiar example is the one in 12-edo which is normally described in harmonic analysis as I - vi - ii - V - I, in which the syntonic comma is tempered out; hence the name. A full description of the discrepancies between the 12-edo and just intonation versions of this progression is given the xenharmonic bridge definition.
A different example of a "comma pump" progression, composed by Graham Breed in blackjack tuning, may be found about 4/5 of the way down on Monzo, The Blackjack Scale.
The tonalsoft.com website is almost entirely the work of one person: me, Joe Monzo. Please reward me for my knowledge and effort by choosing your preferred level of financial support. Thank you.