This is the 68th most frequent Armenian word.
մինչև
"Մինչև" means "until" or "up to" in English.
In this sentence, "մինչև" is used as a conjunction meaning "until," indicating the time up to which the action of waiting occurs.
Ես սպասեցի մինչև անձրևը դադարի։
I waited until the rain stopped.
Here, "մինչև" introduces a temporal clause, specifying the duration of an action in the main sentence.
Նա գնաց դեպի օվկիանոս, մինչև որ արևը մայր մտնի։
He went to the ocean until the sun set.
"Մինչև" in this case creates a condition describing the extent or limit up to which the reminder is relevant.