首字母缩写,来源取决于具体含义:Police Department(19世纪)、Parkinson's Disease(医学命名源自James Parkinson医生)
PD day — 指专业发展日(Professional Development day),学校或公司用于员工培训的工作日。
“Teachers will attend workshops during the PD day.”
(教师们将在专业发展日参加研讨会。)