bot ‧ tle ‧ neck /ˈbɒtlnek $ ˈbɑː-/ BrE AmE noun [countable]
1 . a place in a road where the traffic cannot pass easily, so that there are a lot of delays
2 . a delay in one stage of a process that makes the whole process take longer:
Understaffing has caused a real bottleneck.