I often see these weird translations sometimes of sibling-in-law (or sister-in-law or brother-in-law) but what they really mean is step-sibling (or step-sister or step-brother).

I had the strangest feeling that there's some lost in translation thingy and then I found this (which is for sisters) :

Finally, giri no can also mean ‘step’ as in ‘stepsister’. The Japanese have a conservative stance on divorce, hence, there is no exact word for step siblings.

  1. Is it true step-sibling is translated the same as sibling-in-law?

  2. If yes: In practice, how is this dealt with? I imagine

'My "sibling-in-law" is coming over.' / 'Sibling of your spouse? Or spouse of your sibling?' / 'I actually mean my parent's 2nd spouse's child...'

or just skipping straight

  1. If yes: Maybe not quite on-topic, but well, step-siblings may arise from being widows or adoptive parents, so I don't really see this as a divorce thing necessarily, so I think there would be a need to distinguish the 2 concepts. What's up with that?

  2. If no: then ok what's going on with the above quote please?

Possibly related, maybe even a duplicate: Is the kanji for sister-in-law and step sister the same?

  • 1
    Uncertain of veracity so adding as a comment -- I recall learning that the "step" vs. "in-law" distinction is a fuzzy one in Japanese. One workaround I was told about is using the term 「再婚【さいこん】の」 to clarify the "step" meaning. That might only work clearly with step-parents, though, I'm not sure. Sep 28, 2022 at 8:54

1 Answer 1


The short answer is yes, the same word is used for step siblings and siblings-in-law. After all, step siblings are just siblings in legal terms, so I don't think it is particularly odd.

For simplicity, just consider a younger sister(-ish) who is not biologically related to you and a situation where you introduce her to someone outside family.

  • If she is your spouse's sister, she is introduced most probably as 義妹{ぎまい} or 義理{ぎり}の妹{いもうと} (or simply 妻{つま}/夫{おっと}の妹).
  • If she is a step-sister of yours (i.e., a child from your parent's previous marriage or a sibling by adoption), then you are likely to introduce her just as 妹. Later you may 'reveal' that she is not sister by blood, in which case you say she is a 義理の妹.

That is, 義理の妹/義妹 can be used for step-sister and sister-in-law, but step sister is less frequently mentioned as such. Rather, in ordinary conversations, there is no explicit distinction between blood-related siblings and step-siblings. This may depend on each person, of course.

Half-siblings are called 異母妹{いぼまい} (same father) or 異父妹{いふまい} (same mother). Mutatis mutandis for other types. In speech, the former is more commonly called はらちがいの妹 and the latter is just 父親が違う (there is a word たねちがい, but I think it is not so commonly used). And these won't be mentioned most of the time.

Overall, I guess these things are similar elsewhere, you don't necessarily disclose relationships so that it sounds she is a family member.

For mother, there are specific terms although there're still some ambiguities.

  • 義母{ぎぼ} spouse's mother
  • 養母{ようぼ} adoptive mother
  • 継母{ままはは} step-mother (someone who became your mother by marrying your father)
  • 1
    Suggestion: "not a real sister" carries a strongly negative connotation in English. I might suggest different wording, perhaps "not a sister by blood". Sep 28, 2022 at 17:30
  • I'll take your word for it for now but I may come back someday. Thanks sundowner !
    – BCLC
    Oct 5, 2022 at 14:55
  • 1
    @EiríkrÚtlendi , sundowner is this is the same question as mine? Does Japanese not distinguish between in-laws and step-family members?
    – BCLC
  • @BCLC Yes, looks like that. But may be the question is not specific to siblings.
    – sundowner
    20 hours ago

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