What regular expression will match "East", "West", "North", or "South" but not "East Coast"? In other words, I need an exact match of any of these 4 words.

For instance, if my current regex is /East|West|North|South/ it will match "North 1" and "east" and "North West", which I don't want. I need it to be able to exactly match one or all of these distinct possible words.