n, pl  -a*ses   :  infestation with or disease caused by filarial worms of the genus Onchocerca : esp  :  a human disease caused by a worm (O. volvulus) that is native to Africa but is now present in parts of tropical America and is transmitted by several blackflies - called also onchocercosis , river blindness  - compare CRAW-CRAW  .
 
 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2024.