A person who unquestioningly believes any (or possibly every) myth, no matter how incredulous, about the cutting power, efficiency, design, manufacture, materials (typically the steel) and other attributes of the katana (whether an artifact or a replica), especially in the hands of a samurai, ninja or some other action hero. Typically, the katanatard will also feel the need to make similar extravagant claims him/herself to everyone else (especially any skeptics), in spite of a typically superficial knowledge at best of militaria and military history. Often also a japanophile, sometimes also an otaku, and possibly, but not necessarily, also someone with a sexual fetish for the katana.
Origin: Blend of "katana" and "retard", probably modeled on "fucktard" and similar words with -tard as the second element.
I heard this one guy on the boards go: "European plate armor? That's the best you can do? Please. An Edo-Period katana could cleave a Sherman Tank in two." Damn katanatards these days...
the act of an indigenous American (ie: Native American) male performing coitus with a non-indigenous female.
Ennit? I gave that girl the Native Ballslap.