The Oxford Thesaurus An A-Z Dictionary of Synonyms - significantadj.

1) important, weighty, momentous, consequential, critical, substantial, substantive, noteworthy, notable, valuable, valued, meritorious, outstanding, impressive, historic, relevant, signal: Appleton made significant contributions to knowledge about the ionosphere. 2) meaningful, eloquent, pithy, expressive, pregnant, suggestive, informative: It is significant that they prefer the term Britain to England, Scotland, and Wales .