Forum how to make a "word-link"

[محروم.كوم]

How to set something like this:

When I( or any other member) write a cretain word in a post i want it to contain a link to another post/website.so when one clicks at, it directly moves there him. i want that to work every time when the certain word comes.

is this possible to do? __DEFINE_LIKE_SHARE__