Longman Dictionary of Contemporary English
Wiktionary
n. A letter that is written generically with blanks to be filled in with individual details, often sent in bulk, and frequently regarded as impersonal.
WordNet
n. a letter that is printed in multiple copies and mailed to a list of recipients
Wikipedia
A form letter is a letter written from a template, rather than being specially composed for a specific recipient. The most general kind of form letter consists of one or more regions of boilerplate text interspersed with one or more substitution placeholders.
Although form letters are generally intended for a wide audience, many form letters include stylistic elements or features intended to appear specifically tailored to the recipient—for example, they might be signed by autopen and use features such as mail merge to automatically insert the names of individual recipients.
Usage examples of "form letter".
We worried about this until a friend of mine in Massachusetts sent me a copy of a form letter he’.
The Kee hui was therefore on very short rations, and Hong Kong sent a form letter to all the Kees studying on the mainland—.
Avi doesn't want them talking to Secret Admirers for fear that they will later be accused of stealing someone's ideas, so the reply to all of these e-mails is a form letter that Avi paid some intellectual property lawyer about ten thousand dollars to draft.