umukōbwabo (aba-  1  class 1
singular: umu-
plural: aba-
  
1. daughter of her sister, 2. daughter of his brother
daughter    umukōbwa
(of my, your, his sister if one is girlof my, your, his brother if one is boy) umukōbwācu, umukōbwānyu, umukōbwābo
En-En dictionary 
niece    (daughter of sister, if a girl; daughter of brother, if boy) umukōbwacu, umukōbwanyu, umukōbwabo
(daughter of brother, if one is a girl) umusēngezana
(daughter of one's sister if one is a boy) umwīshwa
En-En dictionary