In Influent, the language learning game, 規{き}則{そく}性{せい}の無{な}い is used to mean 'random'. In checking the term, I see that it does appear in usage, though the dictionary I use (jisho.org) does not list the term, instead listing such terms as 出鱈目, 行き当たりばったり, and 当ても無い, among others. Is 規則性の無い just rarely used in favour of one of the other terms listed? Does 規則性の無い mean 'random, by chance, or without pattern', or does it have a different meaning than what was taught? If it does mean random, what would the connotations of the term be?


The phrase 「規則性のない」 surely can mean "random", but if you used it everytime you wanted to say "random", it would be regarded as an unnatural word choice at least half the time.

「規則性のない」 literally means "lacking regularity" and that is what the phrase mostly means to us Japanese-speakers. To call something 「規則性のない」, one needs to observe it for at least a certain amount of time.

To call something "random", one would often only need to observe a single occurance of something, wouldn't one? If I asked you a question and you thought it random, you would call it a random question, right? You cannot use the phrase 「規則性のない」 in that situation. You would need to be asked at least a few questions before labeling the question pattern as 「規則性のない」.

「規則性のある/ない」 are good phrases to use indeed. Unlike 「[出鱈目]{でたらめ}」 and 「行き[当]{あ}たりばったり」, which are fairly informal, it sounds pretty formal and we do not use it in casual daily conversation.

  • To further clarify, if I were to use 規則性のない to discuss a random card draw or roll of the dice, would that be an appropriate use of the term, or would 任意 better fit? Would both work equally well, depending on the level of formality needed? Jun 22 '15 at 8:07
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    @jimbotherisenclown: In the where probabilistic phenomena are discussed, I would use the transliterated word 「ランダム」. For the record, "任意" sounds "arbitrary" rather than "random."
    – eltonjohn
    Jun 24 '15 at 6:53

First, a verbatim translation of 規則性の無い is "without regularity". So it means "random" in the sense of "without specific patterns."

If your dictionary lists 出鱈目, 行き当たりばったり, and 当ても無い for translation candidates of "random" and does not list 規則性の無い, chances are that the editor regarded 規則性の無い to be too formal for their intended readers.

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