Understanding until and till
Q1. Wait here ___ I return
UNTIL is more formal. TILL is informal but correct. Waiting is required. Patience is tested.
Q2. The shop is open ___ 9 PM
UNTIL marks the endpoint. Nine PM is the closing time. Shopping can commence.
Q3. I cannot stay ___ tomorrow
UNTIL indicates the time limit. Tomorrow is too far. Priorities exist.
Q4. ___ next time, farewell
UNTIL is preferred in formal farewells. Parting is temporary. Returns are anticipated.
Q5. Which sentence is correct?
Both are correct. UNTIL is more formal. TILL is informal. Monday is the deadline.