* Allow: This is a direct opposite of forbid, meaning to give permission.
* Permit: Similar to allow, but with a slightly more formal connotation.
* Authorize: To give official permission.
* Encourage: To promote or support something.
* Sanction: To officially approve or support something.
* Grant: To give something, often as a right or privilege.
The best antonym will depend on the specific situation and the nuances of the meaning of "forbid."