Orthography
Alphabet — Number of Letters
The Umbundu alphabet consists of twenty letters:
Vowels (5): a, e, i, o, u
Consonants (15): f, h, j, k, l, m, n, p, s, t, v, w, y, and two digraphs: ng, nj
The letters b, c, d, g, q, r, x, z of the English alphabet do not occur as independent
letters. The sounds they represent are expressed by combinations:
b is written mb d is written nd
g is written ng j is written nj (before a vowel)
(Stover, Observations upon the Grammatical Structure of the Umbundu, 1885, §1)