The Collaborative International Dictionary of English v.0.48:

Pseudopodium \Pseu`do*po"di*um\, n.; pl. Pseudopodia. [NL.]
   Same as Pseudopod.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pseudopodium
    n 1: temporary outgrowth used by some microorganisms as an organ
         of feeding or locomotion [syn: pseudopod, pseudopodium]