Example: A significant change in tax laws.
A significant change in the Constitution.
A significant contribution.
Significant details.
Statistically significant.
Fitted or designed to signify or make known somethingl having a meaning; standing as a sign or token; expressive or suggestive; as, a significant word or sound; a significant look.(adjective)
source: webster1913
noun (n)
That which has significance; a sign; a token; a symbol.(noun)