Translation

both... and / in addition to / as well as / moreover

Meaning

Not only... but also adds an additional and often more important or surprising element to what was already stated. It emphasizes that BOTH things are true, with the 'but also' part being the stronger point. 'She is not only talented but also hardworking.' (= She is talented AND hardworking — hardworking adds to/reinforces talented) 'The course covers not only grammar but also pronunciation and vocabulary.' Key grammar: when not only begins a sentence, the subject and verb often invert in formal English: 'Not only did he fail the test, but he also didn't apologize.' (inverted: did he, not he did)

Examples

• 彼は歌が上手いだけでなく、演奏もできる。
  He is not only a good singer but also a skilled musician.
• その映画は面白いだけでなく、考えさせられる内容でもある。
  The film is not only entertaining but also thought-provoking.