any of numerous small to microscopic arachnids of the subclass Acari, including species that are parasitic on animals and plants or that feed on decaying matter and stored foods.

noun

crumb , dab , dash , dot , dram , drop , fragment , grain , iota , jot , minim , modicum , molecule , ort , ounce , particle , scrap , scruple , shred , smidgen , speck , tittle , trifle , whit , acarid , atom , bit , bug , insect , minute , mote , nit , parasite , tick