1. Primitive makeshift bandage used to extract puss from a wound
2. Someone who is a complete knob, arsehole etc... The subject is not necessarily always a knob, rather it is normally used to refer to a mate who is being a dick at that particluar time.
As Rootler White would say down the Cavern Bar Church St Newry.
In a derogatory tone 'what r u onabout ye Poultice'