plain·clothes·man or plain·clothes man 
(plānklōzmən, -klōthz-)
(plānklōzmən, -klōthz-)n.
A member of a police force, especially a detective, who wears civilian clothes on duty.
- programmed cell death
- programmed instruction
- programmer
- programming
- programming language
- program music
- program trader
- program trading
- progress
- progression
- progressional
- progressive
- progressive education
- progressively
- progressiveness
- Progressive Party
- progressivism
- progressivist
- progressivistic
- progressivity
- proguanil
- prohibit
- prohibition
- prohibitionism
- prohibitionist