This is the 2000th most frequent Russian word.
уверенность
Confidence; assurance.
Here, 'уверенность' refers to a positive feeling and belief about forthcoming success.
У него была уверенность в успехе.
He had confidence in success.
The word 'уверенность' is related to a strong belief in one's ability to solve a problem.
Уверенность в решении вопроса помогла ей преодолеть трудности.
Confidence in resolving the issue helped her overcome difficulties.
The term 'уверенность' implies a generalized self-assurance required for performing in public.