replace and substitute

Tu Yu

New Member
Dear everyone,

How to distinguish between "replace and substitute".

Such as:
1.I will create a new part number in SAP system, please replace/substiture the new one by/with/for the old one.
2.At present in our company, the new product with the most powerful function than old product. So we have to give our customer a suggestion what different between them. We also hope that our customer will use new product replace/substiture old product.

Thanks for everyone.
  • Kelly B

    Senior Member
    USA English
    I think it is more common to replace an old part with a new or better one. A substitute is not quite as good as the preferred or original part, but it will be good enough to do the job if you cannot get the part you really want. Here, replace (with) would sound better to me.
    The way that most people use it is

    You replace something with something/someone better.
    Ex. I replaced john because he wasn't doing his job
    I replaced the nozzle because it was broken.

    You substitute something with something/someone of equal value
    Ex. I substituted john out of the game because he was tired.

    Thats my 2cents but I could be incorrect, im no english teacher


    Senior Member
    American English
    Substitute often has the implication of being temporary--I will substitute for the teacher when s/he is on vacation (she will return). But if you replace the teacher it is more likely you have taken the job for good. This is not a hard and fast rule, but is usually true.

    A substitute can sometimes be better that the original, however, just like a substitute teacher can be better than the permanent one. But, again, this is not always true. Often in advertisements you will see the phrase "Accept no substitute"--this means be sure to buy the product they're advertising, and don't settle for anything else (by implication) not as good.

    Obvously, "substitute" can be either a noun or verb, but "replace" is only a verb, and "replacement" is the equivalent noun.


    New Member
    What about mathematical expressions? For example: "replacing/substituting this x value in equation #1 you can find the solution of the system." Should I use replace or substitute?


    Senior Member
    English (UK then US)
    In mathematics I think the word used is substitute, if only by convention. I never heard replace to describe that specific operation but I learned my maths a long time ago and the word may have been replaced by now ;D


    Senior Member
    British English
    Although very similar, my take on this does differ from what has already been put forward. Personally, I replace like for like and substitute with something different. Therefore, I would replace a car tyre (swapping one tyre for another), but I would substitute margarine with butter in a cake recipe (since they're not the same thing).

    Granted, manufacturers will often make modifications to improve their replacement parts, so what you replace with may well not be exactly the same. However, if it's designed to slot straight in and do the same work as the old bit without other modifications being needed, then "replace" still works fine.

    For this reason, I believe mathematical equations talk of substitution because you're not swapping like with like. You're not swapping one x with a different x; you're throwing in a "y + 3" (for example) instead.


    New Member
    This is a "hobby-horse" of mine. The two words have become confused through the use of the word "substitute" in football. In that sport, a player is said to be substituted when he is in fact being replaced. In the original meaning of the word, it is the player being sent on who is substituted (for the one coming off the field). As far as I know, in Rugby football, the player coming off is said to be replaced.

    Because of this confusion one quite frequently gets examples where it is impossible to tell what is being substituted and what is being replaced.
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