kūmbure     perhaps, maybe, probably
 kumbure : polite imperative of...
gukūmbura (-kūmbuye)     v    to be lonesome for, to long for, to miss
maybe    kūmbure, nkeka, kur'ubu, hashobora, ndibaza, yomba
En-En dictionary 
perhaps    kūmbure, kur'ubu, nkēka, hashobora, yomba
En-En dictionary 
probably    umēnga, umēngo, kūmbure
En-En dictionary 
 kumbure found in: Kirundi I (Study lessons)
lesson 44   Some verbs
lesson 45   Verb –zi (To know)