SIB
SIBB
SIBBS
SIBILANCE
SIBILANCES
SIBILANCIES
SIBILANCY
SIBILANT
SIBILANTLY
SIBILANTS
SIBILATE
SIBILATED
SIBILATES
SIBILATING
SIBILATION
SIBILATIONS
SIBILATOR
SIBILATORS
SIBILATORY
SIBILOUS
SIBLING
SIBLINGS
SIBS
SIBSHIP
SIBSHIPS
SIBYL
SIBYLIC
SIBYLLIC
SIBYLLINE
SIBYLS

30 words start with SIB.