How to say "extensively" in Japanese

• 手広くてびろくCommon
  adverbCovers 'extensively' when the point is scale: doing something on an extensive scale rather than in a narrowly limited way. A common word, natural for describing how widely someone's activities or operations reach.
• あまねく
  adverbCovers 'extensively' as 'far and wide, everywhere': something extending to or reaching every part, with an all-encompassing feel. Less common, and usually written in kana alone rather than with kanji.
• 広くひろく
  adverbCovers 'extensively' in the plain sense of 'widely': extending over a broad range, or holding universally, as with something known far and wide. A straightforward option, though a less common match for this English word.
• 大きくおおきく
  adverbA marginal match: it really means 'in a big way' or 'on a grand scale', not 'extensively' as broad coverage. Seldom the word you want unless the emphasis is on grandness of scale.
  お母かあさんは目めを大おおきく開ひらいた。↗

  His mother opened her eyes wide.

Choose 「手広く」 for doing something on an extensive scale, 「あまねく」 for something reaching everywhere, 「広く」 for plain 'widely' or universal reach; 「大きく」 means 'in a big way' and is rarely the right choice for 'extensively'.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 手広くてびろくwidely
• あまねくwidely
• 広くひろくwidely
• 大きくおおきくin a big way