Quick Definition: Non-science that looks like science
From Rational Wiki:
Pseudoscience is any belief system or methodology which tries to gain legitimacy by wearing the trappings of science, but fails to abide by the rigorous methodology and standards of evidence that are the marks of true science. Although pseudoscience is designed to have the appearance of being scientific, it lacks any of the substance of science.
Promoters of pseudoscience often adopt the vocabulary of science, describing conjectures as theories or laws, often providing supposed evidence from observation, expert testimonials, or even developing what appear to be mathematical models of their ideas. However, in pseudoscience there is no real honest attempt to follow the scientific method, provide falsifiable predictions, or develop double blind experiments. Pseudoscientists often use the tactic of cheating the scientific method.