SIS
SISAL
SISALS
SISERARIES
SISERARY
SISES
SISKIN
SISKINS
SISS
SISSES
SISSIER
SISSIES
SISSIEST
SISSIFIED
SISSINESS
SISSINESSES
SISSOO
SISSOOS
SISSY
SISSYISH
SISSYNESS
SISSYNESSES
SIST
SISTED
SISTER
SISTERED
SISTERHOOD
SISTERHOODS
SISTERING
SISTERLESS
SISTERLIKE
SISTERLINESS
SISTERLINESSES
SISTERLY
SISTERS
SISTING
SISTRA
SISTROID
SISTRUM
SISTRUMS
SISTS

41 words start with SIS.