an·no·ta·tion \ˌ ̷ ̷ ̷ ̷ˈtāshən\noun (-s) Etymology: Middle English annotacioun, from Latin annotation-, annotatio, from annotatus + -ion, -io -ion 1.: the act of annotating 2. a.: a note added by way of comment or explanation < annotations on the text of an author > b.: an informational and descriptive note especially about a book < annotations on the newest acquisitions of the public library > 3.: a rescript in reply to a private citizen