people
"p"
A six letter word that starts with N and includes an I and a P is NIPPLE.
plans
Particle.
The silent letter in "mnemonic" is the "m" at the beginning of the word. In "pneumonia," the silent letter is the "p" at the beginning of the word.
Another word for holy is pious.
peripheral
prow
poignant
presume
props
prompt? :P