Which term is used incorrectly in this sentence: The mailperson's job is to put the envelope's in every mailbox on the block?

The term "envelope's" is used incorrectly because it employs an unnecessary apostrophe, which indicates possession. In this context, the sentence refers to multiple envelopes, so the correct form should simply be "envelopes" without the apostrophe, as it is meant to indicate the plural form rather than possession. The role of the mailperson involves delivering multiple envelopes, thus making it clear that the envelopes belong in the mailboxes without indicating any sort of ownership. Therefore, using "envelopes" correctly communicates that the mailperson is handling various envelopes, fitting the intended meaning of the sentence.