How to say "previously" in Japanese

• かねてJLPT N1approx.Common
  adverb, no-adjectiveFor 'previously' when something has been the case for quite a while — a long-standing acquaintance, wish, or arrangement. It carries the nuance 'for some time back' rather than a single earlier point.
• 未然みぜんCommon
  nounReally 'before it happens': it concerns the state before something occurs, chiefly in contexts of preventing trouble before it arises. As a translation of 'previously' it is marginal — not the ordinary adverb for 'earlier'.
  政府せいふは感染かんせんの拡大かくだいを未然みぜんに防ふせぐための適切てきせつな措置そちを取とらなかった。↗

  The government didn't take appropriate measures to prevent the infection from spreading.
• 先にさきにJLPT N1approx.Common
  adverbThe plain adverb for 'earlier': something happened before a reference point, or one person acts before another. For plain 'previously' meaning 'earlier', this is usually the word you want.
• 前もってまえもってJLPT N1approx.Common
  adverbChiefly 'in advance, beforehand': doing or arranging something ahead of an event, such as letting people know ahead of time. Its 'previously' reading keeps that anticipatory flavor rather than simply pointing to an earlier time.
  私は前まえもってあなたに知しらせる。↗

  I will let you know in advance.
• お先におさきにJLPT N2approx.Common
  adverbThe polite (teineigo) counterpart of 先に, used when leaving ahead of others or going before someone. For the general sense 'previously' it is seldom the word you want; it serves that courteous 'before you' moment.

For 'previously' meaning 'for some time back' use 「かねて」; for plain 'earlier' use 「先に」; for doing something in advance use 「前もって」; 未然 is really 'before it happens', and 「お先に」 is the polite 'before you'.

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

• かねてpreviously
• 未然みぜんbefore it happens
• 先にさきにpreviously
• 前もってまえもってin advance
• お先におさきにbefore
• この前このまえthe other day
• あらかじめbeforehand
• 前方まえかたbefore
• かねてよりpreviously
• すでにpreviously
• 前まえbefore
• 以前いぜんthe past
• 元もとformerly