The word "vastly" in English means: To a very great extent or degree., Very much; considerably..
The phonetic transcription of "vastly" is /ˈvɑːst.li/ in British English and /ˈvæst.li/ in American English. Click the 🔊 button to hear both pronunciations.
Synonyms for "vastly": greatly, significantly, immensely, enormously.
Example usage of "vastly": "The situation has vastly improved since yesterday.". More examples on the page.