That which has significance; a sign; a token; a symbol.
"The ancient ring served as a significant of his commitment to the family legacy."
"The significance of his discovery changed the course of history."
important in effect or meaning
"a significant change in tax laws"
"a significant change in the Constitution"
"a significant contribution"
"significant details"
"statistically significant"
too closely correlated to be attributed to chance and therefore indicating a systematic relation
"the interaction effect is significant at the .01 level"
"no significant difference was found"
rich in significance or implication
"a meaning look"
"a significant silence"
Signifying something; carrying meaning.
"The silence between them was significant, speaking volumes without a single word being spoken."
In plain English: Significant means something is important enough to matter or make a real difference.
"The project was significant because it changed how we work every day."
Usage: Use significant to describe facts, events, or results that are large enough in size or importance to matter rather than being trivial. Do not confuse it with the verb signify when you need an adjective indicating statistical relevance or major consequence.
The word significant comes from the Latin significans, which originally meant "making a sign." It entered English to describe something that clearly indicates or implies meaning through signs.