ravine    imānga, ikimānga, umukuku
En-En dictionary 
imānga (ama-)     5  class 5
singular: i-,iri-
plural: ama-
  
cliff, ravine
ikimānga (ibi-  4  class 4
singular: iki-,ic-
plural: ibi-,ivy-
  
cliff, ravine
umukuku (imi-)     2  class 2
singular: umu-
plural: imi-
  
1. ditch, trench, ravine, 2. line, row (of people or animals), 3. herd of animals (tame or wild)