PSI
PSILANTHROPIC
PSILANTHROPIES
PSILANTHROPISM
PSILANTHROPISMS
PSILANTHROPIST
PSILANTHROPISTS
PSILANTHROPY
PSILOCIN
PSILOCINS
PSILOCYBIN
PSILOCYBINS
PSILOMELANE
PSILOMELANES
PSILOPHYTE
PSILOPHYTES
PSILOPHYTIC
PSILOSES
PSILOSIS
PSILOTIC
PSION
PSIONIC
PSIONICS
PSIONS
PSIS
PSITTACINE
PSITTACINES
PSITTACOSES
PSITTACOSIS
PSITTACOTIC

30 words start with PSI.