Pseudoarchaeology is described in Wikipedia as referring to interpretations of the past from outside of the archaeological science community, which reject the accepted datagathering and analytical methods of the discipline(a). In recent times it appears to have been used as a derogatory epithet and frequently applied to successful authors such as Graham Hancock or Andrew Collins, I suspect sometimes with a tinge of jealousy.
However, there are many independent researchers who think that they can replace evidence with assertion, reason with rant or commonsense with nonsense.
The abandonment of the scientific method as most pseudoarchaeologists have done is just foolish. A recent article(b) on the subject is worth a look.