7 letter words:
subsist9,
titbits9,
tubists9,
6 letter words:
bututs8,
titbit8,
tubist8,
tussis6,
tuttis6,
5 letter words:
fists8,
sifts8,
tufts8,
bitts7,
busts7,
butts7,
butut7,
stubs7,
situs5,
suits5,
titis5,
tutti5,
tutus5,
4 letter words:
fibs9,
fubs9,
fist7,
fits7,
fuss7,
sift7,
tuft7,
bits6,
bitt6,
buss6,
bust6,
buts6,
butt6,
ibis6,
sibs6,
stub6,
subs6,
tubs6,
sits4,
suit4,
suss4,
titi4,
tits4,
tuis4,
tuts4,
tutu4,
3 letter words:
fib8,
fub8,
fit6,
ifs6,
bis5,
bit5,
bus5,
but5,
sib5,
sub5,
tub5,
its3,
sis3,
sit3,
tis3,
tit3,
tui3,
tut3,
uts3,
2 letter words:
if5,
bi4,
is2,
it2,
si2,
ti2,
us2,
ut2,