Regression rhymes with:
progression, aggression, nonaggression, progression, aggression, digression, nonaggression, progression, transgression, aggression, compression, decompression, depression, digression, discretion, expression, freshen, impression, indiscretion, misimpression, nonaggression, oppression, progression, repression, suppression, transgression
Regression sounds like:
richarson, richerson, rickerson, rogerson