How to say "speculation" in Japanese

• 憶測おくそくCommon
  noun, suru verb, transitive verbCovers speculation in the sense of guessing or conjecturing without firm evidence, often about motives or events. It carries a nuance of unverified talk, as in media speculation about a scandal.
• 投機とうきCommon
  nounCovers speculation in the financial sense: risking money in stocks or ventures hoping for profit. It often carries a slightly negative nuance of gambling-like risk-taking.
  彼かれは投機とうきに手てを出だして財産ざいさんの大半たいはんを失うしなった。↗

  He lost the greater part of his fortune in speculation.
• 思索しさくCommon
  noun, suru verb, transitive verbCovers speculation as deep, contemplative thought or philosophical meditation. This sense of 'speculation' is intellectual reflection rather than guessing about facts or investing money.
  彼かれらはその体系たいけいを大変たいへんな思索しさくと労力ろうりょくを費ついやして仕上しあげた。↗

  They worked out the system with much thought and labor.
• 下馬評げばひょうCommon
  nounRefers to informal speculation, rumor, or gossip circulating before an outcome is known, such as predictions about an election. As speculation it is inherently hearsay, not reasoned judgment.
• 相場そうばJLPT N1approx.Common
  nounGlossed as speculation on stocks, this word primarily means market price or market conditions; its 'speculation' sense is tied to trading activity. For speculation in general, 投機 is the usual choice.

Use 憶測 for unverified guessing, 投機 and 相場 for financial speculation, 思索 for abstract thinking or contemplation, and 下馬評 for pre-event rumors about an outcome.

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

• 憶測おくそくguess
• 投機とうきspeculation
• 思索しさくspeculation
• 下馬評げばひょうrumor
• 射幸しゃこうspeculation
• スペキュレーションspeculation (e.g. in shares)
• 思弁しべんspeculation
• 憶説おくせつhypothesis
• 推考すいこうsurmising
• 揣摩臆測しまおくそくconjectures and surmises
• テオリアcontemplation
• 揣摩しまconjecture
• 相場そうばspeculation (e.g. on stocks)
• 博打ばくちspeculation
• 先物買いさきものがいspeculation
• やまguess
• 思惑おもわくspeculation