User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-4933023-20121014232416/@comment-124.148.228.55-20121018232659

Pseudo means "like" or "similar to" or sometimes "mimic". Traditionally wyverns reffered to the two legged flying wyverns suck as Rathalos, Espinas, Diablos and Doragyurosu. So pseudo wyvern basically means "like a wyvern" or "wyvern mimic".