(figuratively, by extension) An impediment that prohibits the use, adoption, application, etc. of (something).

A bar or pole that can be lowered to block vehicular access through a controlled location, or raised to allow traffic to pass.

plural of boom barrier

(video games) A (usually invisible) plane that causes the player character to die if touched or passed through.

plural of death barrier

(rail transport) A manned barrier at which travel tickets are presented. Modern barriers are machines which can read tickets or where cards can be scanned before allowing passengers through.

plural of ticket barrier

plural of tariff barrier

a barrier to trade between countries in the form of high taxes or duties which may be imposed by a government.

plural of barrier rogue