Inflection of Nouns — Basis of Classification and Demonstrative o

§36–37. BASIS OF CLASSIFICATION

The classification of nouns into classes is not based on meaning (semantic)
but is a historical/formal feature inherited from the Bantu proto-language.
However, some tendencies can be observed:

Class 1 (u-/omu-): persons, people, human beings Class 2 (u-/omu-): plants, inanimates, abstract processes Class 3 (e-/i-): large concrete objects, body parts, abstracts Class 4 (ochi-): instruments, tools, manufactured objects, augmentatives Class 5 (o-): animals, loanwords, words denoting natural phenomena Class 6 (olu-): things of length, extension, pairs Class 7 (oka-): small things, diminutives Class 8 (ou-): pure abstract nouns Class 9 (oku-): body parts attached to verbs, infinitives

Loanwords from Portuguese almost always enter Class 5 (o-, olo-):

gato → ongato (cat) pente → opendo (comb) sapato → osapato (shoe) mesa → omesa (table)

§38. THE DEMONSTRATIVE o
The preformative o- of Class 5 nouns is historically the demonstrative article,
related to the demonstrative pronoun system. It functions as a definite article
in Class 5 but is NOT an article in the other classes (where the full preformative
plays that role).

The demonstrative o is invariable and precedes all nouns of Class 5:

o-ngombe = the ox (or: an ox) o-njila = the bird (or: a bird)

In Class 5 plural, the article o is incorporated into the preformative olo-:

olo-ngombe = the oxen