Sciencey is a term used by Ben Goldacre and others to describe arguments that use the language of science without actually being in any way scientific.
For example, homeopathy advocates use terms like "nano-particles" and "quantum" as special pleading to talk around the obvious problem that typical homeopathy dilutions exceed the Avogadro limit, by which point effectively none of the original material will remain. These are sciencey-sounding arguments but they have no actual scientific basis.
 See also
- Bad Science, Ben Goldacre's website.