Definitions of bastard:

• noun:   derogatory term for a variation that is not genuine; something irregular or inferior or of dubious origin

  Example: "The architecture was a kind of bastard suggesting Gothic but not true Gothic"

• noun:   the illegitimate offspring of unmarried parents
• noun:   insulting terms of address for people who are stupid or irritating or ridiculous
• adjective:   born out of wedlock
• adjective:   fraudulent; having a misleading appearance