1. (particle) has, had, have, will have - a particle used before ordinary verbs and statives denoting that an action is under way or completed, or a state established. It relates to something that has changed from one state to another.
Kua kōwirihia tōna taringa e tana whaea. / His mother has twisted his ear.
(Te Kākano Textbook (Ed. 2): 28; Te Kākano Study Guide (Ed. 1): 19;)
2. (particle) used for a present event if this has just started or is starting right now.
Kua haere tātou! / We're off!
3. (particle) no longer - used before kore to express the loss, absence, destruction or departure of something.
Kua kore he toa i tēnei tāone ināianei. / There are no shops in this town now.
See also kua kore