mighty
1 doughty, forceful, hardy, indomitable, lusty, manful, potent, powerful, puissant, robust, stalwart, stout, strapping, strong, sturdy, vigorous
2 bulky, colossal, elephantine, enormous, gigantic, ginormous (informal) grand, great, huge, humongous or humungous (U.S. slang) immense, large, massive, mega (slang) monumental, prodigious, stellar (informal) stupendous, titanic, towering, tremendous, vast
1 feeble, impotent, weak, weedy (informal) wimpish or wimpy (informal)
2 small, tiny, unimposing, unimpressive