A temporary solution for a problem until a better solution can be found.
Stopgap solutions are usually not the best, but they help for a short time.
Examples:
We used a stopgap to fix the leak in the roof.
The band-aid was just a stopgap until we could get a real bandage.
The stopgap helped for a little while, but we need a better solution.
I used a stopgap to hold my pants up, but I need a belt.
The stopgap fixed the problem for a minute, but then it broke again.
The stopgap was like a small band-aid on a big cut.