I read an article recently where the author used "substract" instead of "subtract". I'm more familiar with the latter word but after doing a bit of googling, it seems that both words are being used, although "subtract" seems more mainstream than the other. Which of the two is more appropriate? Is "substract" even acceptable?
"Subtract" is the word. Though the obsolete word "substract" did exist, any occurrence you see these days is most likely just a common mistake, formed by analogy either with "abstract" or with other languages whose corresponding words do have two ‘s’s.
- An erroneous form of subtract, common in vulgar use.
Note.--Substract was formerly used in analogy with abstract. But in modern usage, it is written according to the Latin, subtract. See this word and its derivatives.
Additionally, I know people who find "substract" very annoying. :-)
It seems that the usage of "substract" is linguistically incorrect. However, I disagree about explaining this usage as a "showing-off". It seems that other languages do contain the letter "s" as in "soustraction" in French. People with a multi-lingual background are more likely to make mistakes, and it is nice if we just point that out to them without prejudice.
If substract is incorrect according to established English usage, this is only because English usage derives this verb from Latin subtraho ‘to subtract’, which excludes the ‑s‑.
In many a Romance language — for example, in Spanish — it derives from the Latin prefix sub‑ coupled with the Latin verb extraho ‘to extract’; hence Spanish substraer. You say ‘sub-tract’ in English where in Spanish we say ‘sub-extract’; hence the extra s.
Substract is incorrect in English, but it could equally have been correct if imported differently.
I found the word "substract" in a memoir written by an old Boston lady in the 1920s, describing how she as a child (during the 1850s) pilfered newspapers from her mother's cache and was able to trade them for candy. I like this usage, as it conveys a kind of arch, sneaky tone better than either "extract" or "subtract" But it's not mathematical at all.