(n.) The all-too-common typographical error masquerading as an apostrophe, especially on the internet. The apostrophe is also known as an inverted comma since, in its correct form, it does not look like this: ' , but rather like a comma that sits above the baseline.
You bloody art directors are all the same. Kindly remove that impostrophe and replace it with the geniune article.
by el revez May 13, 2004
An apostrophe that's unnecessary. Usually added by people who don't have good grammar skills. It can be found almost anywhere, esp. on social media, like Facebook and Twitter, among others.
Bob noticed the sign on the shop's door read, "Open M-F, 9-5; Sat., 10-4; Closed Sunday's," and realized that the apostrophe wasn't necessary. Thus, he deemed it an impostrophe, or an apostrophe trying to "fit in."
by Wordmeister 5000 February 15, 2018