Plural.

Class 1. Umu- (Ngu-mu-).[11] Class 2. Aba (Mba-ba or Nga-ba).[11]
" 3. Umu- (Ngu-mu-). " 4. Imi- (Ngi-mi-).
" 5. Idi (Ndi-di-). " 6. Ama- (Nga-ma-).
" 7. Iki- (Nki-ki-). " 8. Ibi- (Mbi-bi-).
" 9. I-n- or I-ni- (?Ngi-ni-). " 10. Iti-, Izi-, Iti-n-, Izi-n-
(?Ngi-ti-).
" 11. Ulu (Ndu-du-). " 12. Utu (?Ntu-tu-);
often diminutive in sense.
" 13. Aka (?Nka-ka-); usually diminutive, sometimes honorific.
" 14. Ubu- (?Mbu-bu-); sometimes used in a plural sense;
generally employed to indicate abstract nouns.
" 15. Uku (?Nku-ku-); identical with the preposition "to,"
used as an infinitive with verbs, but also with
certain nouns indicating primarily functions of the body.
" 16. Apa (Mpa-pa-); locative; applied to nouns and other
forms of speech to indicate place or position;
identical with the adverb "here," as Ku- is with "there."

To these sixteen prefixes, the use of which is practically common to all
members of the family, might perhaps be added No. 17, _Fi-_ or _Vi-_, a
prefix in the singular number, having a diminutive sense, which is found in
some of the western and north-western Bantu tongues, chiefly in the
northern half of the Congo basin and Cameroon. It is represented as far
east (in the form of _I-_) as the Manyema language on the Upper Congo, near
Tanganyika. This prefix cannot be traced to derivation from any others
among the sixteen, certainly not to No. 8, as it is always used in the
singular. Its corresponding _plural_ prefix is No. 12 (_Tu-_). Prefix No.
18 is _Ogu-_, which has, as a plural prefix, No. 19, _Aga-_. These are both
used in an augmentative sense, and their use seems to be confined to the
Luganda and Masaba dialects, and perhaps some branches of the Unyoro
language. These, like No. 17, are regular prefixes, since they are supplied
with the concord (_-gu-_ and _-ga-_). Lastly, there is the 20th prefix,
_Mu-_, which is really a preposition meaning "in" or "into," often combined
in meaning with another particle, _-ni_, used always as a suffix.[12] The
20th prefix, _Mu-_, however, does not seem to have a complete concord, as
it is only used adjectivally or as a preposition and has no pronominal
accusati