means The process of changing from one state, condition, or stage to another.

from From Latin transitio, 'a going across,' built from trans- ('across') plus the verb ire ('to go') — the same ire that walks through exit, transit, and itinerary. Picture someone literally stepping across a threshold: out of one room, not yet into the next, mid-stride over the line. English borrowed it in the 16th century, and it has been describing that in-between footstep ever since.