6 letter word: S I T A U M

6 letter word:
Autism

4 letter words:
Taus
Tams
Suit
Smut
Smit - past tense of smote. He "smote" him wildly. He lay smitten on the ground.
Must
Mist
Mats
Mast
Aims

3 letter words:
Tau - Greek letter
Tam - short for tam o'shanter: a hat
Sum
Sit
Sim - short sor simulation
Sat
Mus - plural of GReek letter mu
Mat
Mas - plural of "ma" - morethan one mother
Its
Aim