adverb
successfully; with success
Adverb describing that something was accomplished successfully, often after effort or a process.
交渉は首尾よくまとまった。
The negotiations were concluded successfully.
彼は首尾よく試験に合格した。
He passed the exam successfully.
More casual and common; 首尾よく is slightly more formal and often implies a planned or deliberate success.
Compound of 首尾 (beginning and end, outcome) + よく (adverbial form of よい, good). Literally 'with a good outcome'.