n pl :  a cosmopolitan and very large order of the class Arachnida comprising the mites and ticks most of which lack distinct demarcation into cephalothorax and abdomen and have no book lungs, many of which are parasites of plants, animals, or humans, and some of which are vectors of important diseases .
 
   
 
Similar sounding terms:  ac·a·rine  acra·nia or Acrania 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2024.