Is there a word that means “to multiply by 1.5,” or “to increase by 50%?”

I’m familiar with “double,” “triple,” etc. for the first few integers greater than 1. And I assume there isn’t a convention for constructing words for all possible rational multipliers. But 1.5 seems like a sufficiently common case that there might be a special word for it?

  • Is there a single word? Not that I'm aware of. There are several ways of describing it, but they involve more than just one word. Jul 12, 2020 at 16:09
  • There's the single-word decimate, which you could argue means to multiply by 0.9 (or decrease by 10%). But it only works with certain referents, such as populations. Jul 12, 2020 at 16:18
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    Perhaps three-halves (the same style as three-quarters). When we had half penny coins, the sum was referred to as "three-halfpence" or typically "three-ha'pence". Jul 12, 2020 at 16:28
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    "Increase by half" is probably the best-understood term for increasing by 50%. Such terms tend to become ambiguous very easily.
    – Hot Licks
    Jul 12, 2020 at 16:32
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    "Half as much again" is a common idiom but not a single word.
    – Mary
    Jul 12, 2020 at 17:49

1 Answer 1


It doesn’t exist, but you could try inventing something like


Some would quibble, but the prefix sesqui means one-and-a-half, and is used in compound names in chemistry.

Indeed, some have quibbled and suggested the more elegant:




I leave it to the classical scholars and genuine linguists to decide which is preferable.

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    I would maybe say "sesquate".
    – Hot Licks
    Jul 12, 2020 at 17:32
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    Or sesquify, perhaps. Jul 12, 2020 at 17:40
  • Wow. Great words. I have a Ph.D. in chemistry and never heard sesqui before. Must have been the wrong kind of chemistry. Inorganic, I presume. I would go with sesquify. +1 Jul 12, 2020 at 21:05
  • @RichardKayser — I have a bachelors degree in chemistry from the ancient times, but remembered sesquihydrates (or perhaps encountered them later in reagent catalogues when I jumped ship and became a molecular biologist). Google autocomplete led me to sesquioxides, which seem to have more fans.
    – David
    Jul 12, 2020 at 21:12
  • Cool. Good stuff. In retrospect, I have heard the term sesquihydrates. Jul 12, 2020 at 21:15

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