This is the 316th most frequent Hungarian word.
mikor
"When."
The word 'mikor' is used here to ask a question about time, specifically to inquire about when an event will occur.
Mikor megyünk moziba?
When are we going to the cinema?
The word 'mikor' functions as a relative pronoun, introducing a relative clause specifying the time of a past event.
Emlékszel arra a napra, mikor találkoztunk?
Do you remember the day when we met?
In this sentence, 'mikor' introduces a subordinate clause to specify the time aspect of the verb in question.