Letter on position 1 (b) changed: 10 words cubs dubs fubs gubs hubs nubs pubs rubs subs tubs Letter on position 2 (u) changed: 2 words bibs bobs Letter on position 3 (b) changed: 8 words buds bugs bums buns burs buss buts buys Letter on position 4 (s) changed: 3 words buba bubo bubu