The Collaborative International Dictionary
Post-it note \Post"-it note\, n. [From the trademark Post-it registered by the 3M Corporation.] A small sheet of paper having the back part partly covered with a non-permanent gum which allows the note to be attached temporarily to another object, and easily removed without leaving any trace of glue on the object to which it was affixed. Such note papers are sold in pads of varying sizes.
Wiktionary
n. A small piece of paper with an adhesive strip on one side.
Wikipedia
A Post-It note (or sticky note) is a small piece of paper with a re-adherable strip of glue on its back, made for temporarily attaching notes to documents and other surfaces. A unique low-tack pressure-sensitive adhesive allows the notes to be easily attached, removed and even re-posted elsewhere without leaving residue. Originally small yellow squares, Post-It Notes and related products are now available in an array of colors, shapes and sizes.
Although 3M's patent ran out in 1997, "Post-It" and the original notes' distinctive yellow color remain registered company trademarks, with terms such as "repositionable notes" used for similar offerings manufactured by competitors. Despite this, the name has become genericized for all such products in many countries.
Usage examples of "post-it note".
The CIA officer handed over a Post-it note and pointed to a phone.
A yellow Post-it note, affixed to the article, contained Morrison’.
There, a Post-it note on a teletype machine announced that Chief Superintendent Nolan of Special Branch wanted to be informed at once of any death by fire or accident, and the teletype operator lifted a phone and called the appropriate number.
Down there a Navy petty officer had the number on a Post-It note, and read it off.
A Post-it note was affixed to the front page of the Washington Post, just over an article bylined to Bob Holtzman and John Plumber.
Richard had written the Post-it note to himself, several weeks earlier.
That's why they wrote on the grave and put that Post-it note on the tape.
A Post-it note, a Bic pen, the necessities of life, were lost in the debris.