letter head's

noun

1. a printed heading on stationery, especially one giving the name and address of a business concern, an institution, etc.
2. a sheet of paper with such a heading.

noun

1. a sheet of paper printed with one’s address, name, etc, for writing a letter on

n.1868, short for letterheading (1867); from letter (n.1) + head (n.). So called because it was printed at the “head” of the piece of paper.