|Origin:||acertainer, from certain|
as‧cer‧tain [intransitive and transitive]
to find out something:
A postmortem was ordered to try to ascertain the cause of death.
ascertain whether/what/how etc
Tests were conducted to ascertain whether pollution levels have dropped.
Police had ascertained that the dead man knew his killer.
ascertain something from somebody/something
You should ascertain the level of insurance cover from the car rental company.