Initialism of paranoid personality disorder

偏执型人格障碍

Initialism of postpartum depression

产后抑郁症

Initialism of purified protein derivative, used in TB skin tests

纯化蛋白衍生物，用于结核菌素皮试

Initialism of pixels per degree, a VR clarity metric

每度像素，虚拟现实清晰度指标

Abbreviation of protoplanetary disk

原行星盘的缩写

Initialism of paraphenylenediamine, a dye intermediate

对苯二胺，一种染料中间体

Abbreviation of postpaid; postage already paid

邮资已付；已预付邮费的缩写