murky
adjective /ˈmɜːki/
  /ˈmɜːrki/
(comparative murkier, superlative murkiest)
- (of a liquid) not clear; dark or dirty with mud or another substance synonym cloudy
- She gazed into the murky depths of the water.
 - (figurative) The meaning of this sentence remains murky.
 
 - (of air, light, etc.) dark and unpleasant because of smoke, fog, etc.
- a murky night
 - The light was murky and it was difficult to see ahead.
 
 - (disapproving or humorous) (of people’s actions or character) not clearly known and suspected of not being honest
- He had a somewhat murky past.
 - He was involved in the murky world of arms dealing.
 
Extra Examples- He had an extremely murky past.
 - What are you talking about? Some dark secret from your murky past?