"Keenest" Natural Recordings by Native Speakers
The adjective "keenest" is the superlative form of the word "keen", which means:
Having a sharp and piercing sense of sight, smell, or hearing: "The keenest eyes among them spotted the bird nesting in the tree."
Sharp and biting in expression or wit: "His keenest remarks left the audience in stitches."
Having a strong and eager interest or enthusiasm: "She's the keenest fan of the band and always attends their concerts."
In summary, "keenest" describes something or someone that is at its most intense, sharp, or enthusiastic.
Keen means strong or intense. It can also refer to something being sharp or acute, especially in the sense of being insightful or perceptive. A keen observer might notice details that others might miss.