ascertain in WordNet English dictionary

1. be careful or certain to do something; make certain of something
   "He verified that the valves were closed"; "See that the curtains are closed"; "control the quality of the product"
   see  check  insure  see to it  ensure  control  ascertain  assure 
   
2. learn or discover with certainty
   ascertain 
   
3. find out, learn, or determine with certainty, usually by making an inquiry or other effort
   "I want to see whether she speaks French"; "See whether it works"; "find out if he speaks Russian"; "Check whether the train leaves on time"
   determine  check  find out  see  ascertain  watch  learn 
   
4. establish after a calculation, investigation, experiment, survey, or study
   "find the product of two numbers"; "The physicist who found the elusive particle won the Nobel Prize"
   determine  find  find out  ascertain