PURIM is a 5 letter word that starts with P.
\Pu"rim\, n. [Heb. p[=u]r, pl. p[=u]r[imac]m, a lot.]
A Jewish festival, called also the Feast of Lots, instituted
to commemorate the deliverance of the Jews from the
machinations of Haman. --Esther ix. 26.