Concessionary rhymes with:
recessionary, discretionary, recessionary, cautionary, confectionary, confectionery, counterrevolutionary, deflationary, dictionary, discretionary, disinflationary, evolutionary, expansionary, expeditionary, functionary, inflationary, missionary, noninflationary, probationary, reactionary, recessionary, revolutionary, stationary, stationery
Concessionary sounds like:
canzoneri, commissioner, concessionaire, consumer