"Keen" is an adjective that can have a few different meanings depending on the context:

1. Eager or enthusiastic: If someone is keen, it means they have a strong interest or enthusiasm for something. For example, if someone is keen to learn a new language, it means they are eager and enthusiastic about learning it.

2. Sharp or acute: Keen can also mean sharp or acute, especially when referring to senses or perception. For example, if someone has keen eyesight, it means their vision is sharp and clear.

3. Intense or strong: Keen can also describe something that is intense or strong, often used to describe emotions or feelings. For example, if someone has a keen sense of loss, it means they feel a strong and intense sadness or grief.

4. Clever or astute: Keen can also mean clever or astute, especially when referring to intelligence or mental ability. For example, if someone has a keen mind, it means they are quick-witted and intelligent.

Overall, the meaning of "keen" can vary depending on the context in which it is used.