keen in WordNet English dictionary

1. having or demonstrating ability to recognize or draw fine distinctions
   "an acute observer of politics and politicians"; "incisive comments"; "icy knifelike reasoning"; "as sharp and incisive as the stroke of a fang"; "penetrating insight"; "frequent penetrative observations"
   acute  discriminating  incisive  keen  knifelike  penetrating  penetrative  piercing  sharp 
   
2. very good
   "he did a bully job"; "a neat sports car"; "had a great time at the party"; "you look simply smashing"
   bang-up  bully  corking  cracking  dandy  great  groovy  keen  neat  nifty  not bad  peachy  slap-up  swell  smashing 
   
3. painful as if caused by a sharp instrument
   "a cutting wind"; "keen winds"; "knifelike cold"; "piercing knifelike pains"; "piercing cold"; "piercing criticism"; "a stabbing pain"; "lancinating pain"
   cutting  keen  knifelike  piercing  stabbing  lancinate  lancinating 
   
4. intense or sharp
   "suffered exquisite pain"; "felt exquisite pleasure"
   exquisite  keen 
   
5. having a sharp cutting edge or point
   "a keen blade"
   keen 
   

1. a funeral lament sung with loud wailing
   keen 
   

1. express grief verbally
   "we lamented the death of the child"
   lament  keen