having great power or force or potency or effect; "the most powerful government in western Europe"; "his powerful arms"; "a powerful bomb"; "the horse's powerful kick"; "powerful drugs"; "a powerful argument"
characterized by or full of force or strength (often but not necessarily physical); "a forceful speaker"; "a forceful personality"; "forceful measures"; "a forceful plan for peace"
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"