What is the meaning of Barrier?

A structure that bars passage.

An obstacle or impediment.

A boundary or limit.

A node (in government and binding theory) said to intervene between other nodes A and B if it is a potential governor for B, c-commands B, and does not c-command A.

A separation between two areas of the body where specialized cells allow the entry of certain substances but prevent the entry of others.

The lists in a tournament.

A martial exercise of the 15th and 16th centuries.

To block or obstruct with a barrier.

Source: wiktionary.org