p (melting point)

p (post (after))

p (pulse)

P (phosphorus [element])

P-A (posterior-anterior)

P-A (posteroanterior)

P-A (placenta abruption)

P-ANCA (perinuclear antineutrophil cytoplasmic antibody)

p.c. (after meals (post cibos))

p.m. (afternoon/evening (post meridiem))