say it: MAHY-tuh-lee
mightily is an adverb meaning "powerfully or vigorously". It carries 2 recorded senses.
powerfully or vigorously
“he strove mightily to achieve a better position in life”
Definitions, synonyms and semantic relations for mightily come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.