What does "keen" mean?

Enthusiastic, eager, or interested. "Keen" is the British English go-to word for showing genuine interest or willingness. "She's very keen on the idea" means she's genuinely excited about it. It's a small, flexible word that pops up constantly in British conversation, from the office to the pub, and once you start listening for it you'll notice how often native speakers reach for it instead of longer words like "enthusiastic" or "interested."

1. Enthusiastic/eager: "He's really keen to get started." "The new intern is so keen, she arrives early every morning."
2. Interested in someone romantically: "I think she's keen on him." (She likes him.) "He's clearly keen, he keeps texting."
3. Sharp or intense: "A keen eye" (sharp/perceptive). "A keen sense of smell." "She has a keen intellect."
4. Price: "Keen pricing" in British business English means competitively low prices. "We can offer you a keen price" means "We'll give you a good deal."

So no, it is not always about enthusiasm. The "sharp" and "price" meanings are worth remembering, because a learner who only knows the "eager" sense can be baffled by "a keen wind" (biting, cold) or "keen competition" (fierce, intense).

"Keen" often implies eagerness to do something, while "enthusiastic" describes energy and excitement. They overlap significantly, but "keen" is quieter and more understated, which suits the British temperament. You can be quietly keen. It's harder to be quietly enthusiastic.

This is important. "I'm not keen on that idea" is a very British way of expressing strong disapproval without sounding aggressive. It's polite understatement. "Not keen" can mean anything from mild preference against to strong dislike, and tone of voice tells you which. If a colleague says "I'm not keen" in a meeting, they may well mean "absolutely not," delivered gently so nobody loses face.

Learners often forget the preposition. You are keen on a thing or a person, but keen to do something. "She's keen on tennis" is correct. "She's keen to play tennis" is correct. "She's keen tennis" is not. Mixing these up is the most frequent slip, so pause and check whether a noun (on) or a verb (to) follows.

Think of a knife with a "keen" edge, sharp and ready. A keen person is mentally sharp and ready to go. That single image links two of the meanings, the "eager" one and the "perceptive" one, so you only have to remember one picture.

In a work email, "We'd be keen to explore this further" sounds professional and warm. Down the pub, "Fancy a curry later?" "Yeah, I'm keen" is perfectly natural and relaxed. The word travels across registers without changing shape, which is part of why it's so useful.

"Keen" in the enthusiasm sense is heavily British. Americans understand it but rarely say it, and to some American ears it can sound a touch old-fashioned or even posh. Interestingly, Americans do use "keen" for the "sharp/intense" meanings quite happily, as in "a keen eye" or "keen interest." So the sharp senses cross the Atlantic easily, while the "eager" sense stays mostly at home.

"Keen as mustard" is a lovely British idiom meaning extremely enthusiastic. "The new recruits are keen as mustard." It's a bit playful and warm, and it's a nice one to keep in your back pocket for describing someone bursting with willingness.

• "Eager" (often more intense than keen)
• "Enthusiastic" (more energetic)
• "Into it" (casual American English)
• "Up for it" (casual British English)

Casual to professional. Works in most contexts. More common in British English.