0 past simple and past participle of ascertain
1 to discover something:
The police have so far been unable to ascertain the cause of the explosion.
[ + question word ] Have you ascertained whether she's coming or not?
[ + that ] I ascertained that no one could overhear us before I told Otto the news.
When it had been ascertained at what temperatures the maximum number of each species was seen, the counts were thereafter made when these conditions obtained.
Full-time employment status was ascertained by asking respondents how many hours they worked each week, with 35 or more hours denoting full-time.
Momentum cannot be ascertained by observing the steady-state velocity of a body unless its mass is known.
Susceptibility to rheumatic fever have been ascertained because of the poor quality of records in earlier years.
All are vulnerable to software bugs, however, at any time and so the liability of software companies needs to be ascertained.
In addition, the joint effects of pollutants and parasitism on the immune system of the host has not been ascertained.
So far as truth can be ascertained by mortal men, so far as learned, impartial criticism can be final, we have them there.
First, the sample is epidemiologically ascertained, thereby eliminating possible biases associated with treatment-seeking.