keen
UK: kiːn | US: kiːn
adj. sharp or intense (e.g., a keen edge)
adj. highly perceptive or intellectually acute (e.g., a keen mind)
adj. eager or enthusiastic (e.g., keen to participate)
vt. (archaic) to lament or wail mournfully
The word "keen" traces back to Old English cēne, meaning "bold, brave, fierce," derived from Proto-Germanic kōniz (sharp, bold). Its modern senses of "sharp" (literal and figurative) and "eager" evolved from the idea of mental or emotional intensity. The archaic verb form (to lament) stems from Irish caoineadh (mournful wailing), likely influenced by Celtic traditions of vocal grief.
She has a keen eye for detail in her artwork.
The knife’s keen blade sliced through the paper effortlessly.
He was keen to start his new job.
(Archaic) The mourners began to keen at the funeral.
Her keen understanding of physics impressed the professors.