The New Student's Reference Work/P
P (pē), the sixteenth letter, is a voiceless consonant. It is articulated at the lips, and is called a sharp labial, as in cup,pea, spy. Initial p before n, sh, s and t is silent, as in pneumatic, psalm, pshaw, ptarmigan. P also is silent in accompt, corps, raspberry, receipt, sempstress. No native English word begins with pn, ps or pt.