Rhizopoda

from The Century Dictionary.

• In Dujardin's system of classification (1841), the third family of “diversiform infusorians without visible locomotory appendages”—that is, without permanent appendages, as cilia or flagella.
• The lowest class of Protozoa, composed of simple or multiple animalcules without definite or permanent distinction of external parts, and provided with diversiform temporary or permanent pseudopodial prolongations of the bodysubstance, by means of which locomotion, fixation, and ingestion are effected.

from the GNU version of the Collaborative International Dictionary of English.

• noun plural (Zoöl.) An extensive class of Protozoa, including those which have pseudopodia, by means of which they move about and take their food. The principal groups are Lobosa (or Amœbea), Helizoa, Radiolaria, and Foraminifera (or Reticularia). See protozoa.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun creeping protozoans: amoebas and foraminifers