Subject Concord with Vowel Verb Stems

The following verbs starting on vowels have fixed initial vowels which may not be interchanged or omitted:

-aka (share)
-akha (build)
-ala (refuse)
-anda (increase)
-anga (kiss)
-eba (steal)
-ehla (descend)
-ena (be overgrown)
-enda (marry)
-enza (do)
-eqa (jump)
-okha (transfer fire)
-oma (get dry)
-ona (sin, do wrong)
-onda (get thin)
-ondla (nourish)
-onga (be economical, save money)
-opha (bleed)
-osa (roast)
-otha (warm oneself)


There are also verbs which start on vowels which may be interchanged or omitted:
(all the following initial vowels can be omitted, and all except -esuka be replaced with an a-)

-esuka (move away)
-elusa (herd)
-edlula (pass)
-ehlula (conquer)
-ehluka (differ)
-embatha (dress)
-emuka (go away)
-ephuka (get broken)
-ephula (break)
-esula (wipe)

In isiZulu two vowels may never appear next to each other within the same word. Therefore, certain sound changes will take place when subject concords are prefixed to vowel verb stems.

Vowel elision

When subject concords cosisting of a consonant + vowel are prefixed to a vowel verb stem, the vowel of the verb stem is kept and the vowel of the subject concord discarded. This might be better explained by a few examples:

• ngi- + -eba -> ng- + -eba
  Ngeba imali. (I steal money)
• si- + -osa -> s- + -osa
  Sosa inyama yenkukhu. (We roast chicken meat)
• ba- + -ala -> b- + -ala
  Abafana bala ukudlala (The boys refuse to play)
• zi- + -onga -> z- + -onga
  Izintombi zonga imali. (The girls save money)

The only exception is in the classes ulu- and uku- (where the vowel is not elided) and the class ama- where the subject concord a- is elided as a whole:

• a- + -omile -> omile
  Amahhashi omile manje. (The horses are thirsty now)

Consonantalization

Subject concords consisting only of the vowels u- and i-, respectively change to the semi-vowels w- and y-:

• Indoda yala (i- + -ala) ukusebenza. (The man refuses to work)
• Umoya wephula (u- + -ephula) umuthi. (The wind breaks the tree)

Second person singular:

• Welusa (u- + -elusa) izinkomo.

The concords of classes ulu- and uku-
Depending on the nature of the initial vowel, vowel elision or consonantalization may take place when the subject concords of ulu- and uku- are prefixed to vowel verb stems. When prefixed to stems starting with a- and e- the subject concords lu- and ku- become lw- and kw-. When prefixed to stems starting with o-, they become l- and k-.

• lu- + -eba -> lweba ;
  Uhlanya lweba ubisi. (The lunatic steals milk)
• Ukhamba loma (lu- + -oma) kahle. (The claypot dries well)

Long present tense with vowel verb stems
The a- of -ya is elided when it is used with vowel verb stems:

• Siyosa. (We are roasting)
• Ngiyeba. (I am stealing)
• Uyehla. (He is descending / Climbing down)