(plural picket lines)
- (rare) A line or rope held by one or many pickets, chiefly one used for tethering horses.
- (military, rare) A barrier or fortification formed by pickets; a stockade.
- A boundary guarded by a picket, or unit, of soldiers.
- (US) The boundary created by striking workers, generally at the workplace entrance, which other workers are asked not to pass.