[*** \mathrm{keen}^1] |kēn|

SHARP, KEEN, ACUTE mean having or showing alert competence and clear understanding.

SHARP implies quick perception, clever resourcefulness, or sometimes questionable trickiness.

e.g. sharp enough to spot a confidence game

KEEN suggests quickness, enthusiasm, and a penetrating mind.

e.g. a keen observer of the political scene

ACUTE implies a power to penetrate and may suggest subtlety and sharpness of discrimination.

e.g. an acute sense of style

EAGER, AVID, KEEN, ANXIOUS, ATHIRST mean moved by a strong and urgent desire or interest.

EAGER implies ardor and enthusiasm and sometimes impatience at delay or restraint.

e.g. eager to get started

AVID adds to EAGER the implication of insatiability or greed.

e.g. avid for new thrills

KEEN suggests intensity of interest and quick responsiveness in action.

e.g. keen on the latest fashions

ANXIOUS emphasizes fear of frustration or failure or disappointment.

e.g. anxious not to make a social blunder

ATHIRST stresses yearning but not necessarily readiness for action.

e.g. athirst for adventure

1. (of a sense) highly developed:

〖名詞の前で〗鋭い〈五感〉; 鋭敏［明晰］な〈知力など〉

e.g. I have keen eyesight.

having or showing great perception or insight:

〖通例名詞の前で〗強い, 深い〈関心･意識･感覚など〉

e.g. her keen intellect

e.g. a keen understanding of animal psychology.

2. (of the edge or point of a blade) sharp.

｟文｠ 〈刃物などが〉(非常に)切れ味のよい, 鋭い(sharp)(↔ dull, blunt).

(of the air or wind) extremely cold; biting.

｟文｠ 〈風･寒さなどが〉身を切るような, 骨身にしみる.

literary (of a smell, light, or sound) penetrating; clear.

〈音･光などが〉すさまじい, 強烈な; 〈痛みなどが〉痛烈な; 〈においが〉鼻をさす

3. having or showing eagerness or enthusiasm:

｟主に英｠ ; 〖be ～ to do〗 〈人が〉…したいと熱望［切望］して; «…を/…ということを» 切望して «for/that節» ; 〖be ～ for A to do〗 Aが…するのを熱望して(eager)

e.g. keen believers in the monetary system

e.g. a keen desire to learn.

predicative (keen on) interested in or attracted by (someone or something):

〖be ～ on ［about］ A〗 A〈人･物･事〉が大好きで (!Aは〖名詞〗〖動名〗) ; A〈趣味･スポーツなど〉に熱中して; ｟英｠ A〈異性〉に夢中で; 〖通例名詞の前で〗(趣味･仕事･勉強などに)熱心 ［意欲的］な〈人〉

e.g. Bob makes it obvious he's keen on her.

4. predicative North American informal, dated excellent:

｟米俗･やや古｠ ; 〖be ～〗 すばらしい, すてきな.

e.g. I would soon fly to distant stars—how keen!

5. British (of prices) very low; competitive.

｟主に英｠ 〈価格が〉(競争のために)安い, 破格(値)の.

Old English cēne ‘wise, clever’, also ‘brave, daring’, of Germanic origin; related to Dutch koen and German kühn ‘bold, brave’. Current senses date from Middle English.

[*** \mathrm{keen}^2] |kēn|

verb no object

wail in grief for a dead person; sing a keen:

｟主にアイル･文･古｠ (死者に対して)哀歌を歌う; 【死者を】泣き悲しむ［叫ぶ］ «over» .

e.g. the body of Johnny was taken by his own people who keened over him.

make an eerie wailing sound:

e.g. the wind blew and wild birds keened in the sky.

an Irish funeral song accompanied by wailing in lamentation for the dead.

(死者への)哀歌; 泣き悲しむこと

mid 19th century: from Irish caoinim ‘I wail’.