Learner's definition of UNCERTAIN
[more uncertain; most uncertain]
: not certain: such as a : not exactly known or decided : not definite or fixed b : not sure : having some doubt about something
c : not definitely known d : likely to change : not constant or dependable
We are still uncertain of the truth.
She remains uncertain about her plans.
I'm uncertain about how to respond.
in no uncertain terms
: in a very clear and direct way