1) Genus of mites 2) Mite 
Acarus is a genus of mites in the family Acaridae. ...
• (n.) A genus including many species of small mites.
(ak´ә-rәs) a genus of small mites that can cause itch, mange, and other skin diseases. Several species live on plants used as food by humans and burrow under the skin of persons handling them.
Ac'a·rus noun ; plural Acari [ New Latin , from Greek ... the cheese mite, tick.] (Zoology) A genus including many species of small mites. 
Type: Term Pronunciation: ak′ă-rŭs Definitions: 1. A genus of mites of the family Acaridae.
[n] - a mite of the genus Acarus
Acarus (s), Acari (pl) A genus of minute Arachnida, or spider-like animals, embracing the cheese-mite and its congeners; a mite.
genus Acarus noun any of several mites of the order Acarina
a mite, esp. of the genus Acarus.