Is “substract” (versus “subtract”) a proper word?

Question

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?

Answer 1

"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.

Many recent dictionaries do not list "substract". Of "substract", the Century Dictionary (1891) said:

1. An erroneous form of subtract, common in vulgar use.

Webster's Revised Unabridged Dictionary of 1913 called it "obsolete", while the even older version of 1828 said

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. :-)

Answer 2

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.

Answer 3

French people use "substract" mistakingly a lot because in french, the word is "soustraction", which contains the sound "s" inside.

Answer 4

I've never heard of "substract" and, more to the point, neither has my edition of the Oxford English Dictionary. Even if it is a word, assuming that it means the same as "subtract" I can't see any point in preferring it over the better known word, apart from showing off.

Answer 5

I found the word "substract" in a memoir written my an old Boston lady in the 1920s, describing how she as a child (in 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 not mathematical at all.

Answer 6

By looking at the etymology, we can see that "substract" is erroneous. "subtract" is derived from a the Latin compound verb "subtraho", whose supine is "subtractum". There is no form "substraho" of this verb.