1 definition by Coconut Noggin.
British slang, originating from Pilsley, Derbyshire: A weak expletive which shares both its definition and conventions of use with the word bastard. Originally, "mustard" was used to refer to a child born out of wedlock, but through a process of semantic broadening, it is now mostly used as a general pejorative term. It can be used both as a noun (see example one) and an adjectival intensifier (see example two). The word bastard is used in precisely the same way. As an antidote to your ignorance, other examples of intensifiers are: fucking, bloody, chuffing, sodding, etc.
Example one: My phone's such a mustard; the autocorrect feature has made a fool of me yet again.
Example two: Arghh, my mustard phone has caused me ridicule!
Example two: Arghh, my mustard phone has caused me ridicule!
by Coconut Noggin. February 11, 2012