What is "acanthamoeba"

n. Any amoeba of the genus Acanthamoeba, found chiefly in soil. (First attested in the mid 20th century.)Brown, Lesley, ed. ''The Shorter Oxford English Dictionary.'' 5th. Oxford: Oxford University Press, 2003.

Acanthamoeba is a genus of amoebae, one of the most common protozoa in soil, and frequently found in fresh water and other habitats. Acanthamoeba has two evolutive forms, the metabolically active trophozoite and a dormant, stress resistant cyst. Trophozoites are small, usually 15 to 35 μm in length and amoeboid in shape. In nature, Acanthamoeba species are free-living bacterivores, but in certain situations they can cause infections (Acanthamebiasis) in humans and other animals.