Pseudoscience consists of statements, beliefs, or practices that are claimed to be scientific and factual, in the absence of evidence gathered and constrained by appropriate scientific methods. Pseudoscience is often characterized by the following: contradictory, exaggerated or unfalsifiable claims; reliance on confirmation bias rather than rigorous attempts at refutation; lack of openness to evaluation by other experts; and absence of systematic practices when developing theories.

- Pseudoscience, Wikipedia as on 29th November 2017

In simpler, but not so accurate words, pseudoscience is any idea that is not accepted by mainstream scientists. An idea that does not adhere to the scientific method is pseudoscience. However, even if an idea does adhere to a scientific method, it may be pseudoscience.

For instance, the Flat-Earth Theory. This was the page which supports the Flat Earth theory. While this debunks it.