enthusiastic; eager
said of emotion or feeling: intense
taking a keen interest
sharp
a keen blade
having a fine edge or point; sharp
said of the wind: strong and piercing
said of physical or mental faculties: sharp; acute
keen eyesight
a keen intellect
Brit of prices: competitive
keen on
interested in or attracted by (something or somebody)
keenly adv
keenness noun
[Old English cēne brave]