General Antonyms:
* Remember - This is the most direct and common antonym.
* Recall - Similar to remember, but often implies a more conscious effort.
* Recollect - Similar to recall, but can imply a more specific memory.
* Retain - This implies keeping something in mind, often knowledge or information.
Other Antonyms depending on context:
* Know - If you forget something, you don't know it.
* Understand - If you forget how to do something, you don't understand it.
* Learn - If you forget something, you haven't learned it properly.
Examples:
* "I forgot where I put my keys, but then I remembered I left them on the table."
* "I forgot her name, but I recalled we met at a conference last year."
* "I forgot how to solve this equation, so I need to relearn the formula."
The best antonym for "forget" will depend on the specific meaning you want to convey.