There do not seem to be any sutiable synonyms except "planting" (for burying).
Perhaps the synonym sought was for internment, which could include prison.
people
plans
Particle.
"Pristine" is a word that can be synonymous with holy and starts with the letter P.
prow
peripheral
props
poignant
presume
prattle
puce
Pause is a synonym for "to stop". It begins with the letter p.