noun: Initialism of paranoid personality disorder. [(psychiatry) A mental disorder characterized by paranoia and a pervasive, long-standing suspiciousness and generalized mistrust of others.]
noun: Initialism of postpartum depression. [(psychiatry) Depression experienced by a parent, usually the mother, after childbirth.]
noun: Initialism of purified protein derivative.
noun: Initialism of pixels per degree. (a measurement of the visual fidelity of a virtual reality headset)
noun: (astronomy, countable) proplyd; Abbreviation of protoplanetary disc.
