Swap sth for sth

The informal, conversation verb 'swap' can have more than one meaning.

Swap almond milk for regular milk.

Here, "swap" means "substitute". We substitute the second thing for first thing.

He swapped his cupcake for a candy bar.

Here, 'swap' means 'exchange'. We exchange the first thing for the second thing.


The correct interpretation is obtained by thinking about what is being described.


Previously you used 'his cupcake'. The word 'his' made it clear that the person initially possessed the cupcake, thus the 'swap' is an exchange. Now you use 'a cupcake' and it is no longer clear. The phrase is ambiguous. It may or may not be possible to resolve this by examining the context (the surrounding words).


It could mean either "He had a cupcake and gave it up in exchange for a candy bar." or

Sorry, I didn't complete that. I think the best things is to use 'swap X for Y' when you mean 'give up X and get Y in return' and 'swap X with Y' when you mean 'transpose X and Y'.

Or use the appropriate word - exchange, transpose, replace, substitute, etc. Swap is very conversational and informal.

Sorry about taking nearly a month to get back to this.

I agree with you completely; it seems that the ambiguity with the lack of possession is truly unresolvable in written form without any context. That is, the use of "swap X for Y" (and even "swap X with Y") describes an exchange, but there needs to be reference to determine the actual action.

Thanks for the reply!