Letter on position 1 (m) changed: 9 words bums fums gums hums lums rums sums tums vums Letter on position 2 (u) changed: 3 words mams mems moms Letter on position 3 (m) changed: 5 words muds mugs muns muss muts Letter on position 4 (s) changed: 3 words mumm mump mumu