Pen/pen/ Definition 1 of 5Pro Tip 1/3Writing Implement Pen often refers to different types of writing tools used in various settings, from school to art. I need a gel pen for this art project. Pro Tip 2/3Permanent Marks 'Pen' implies ink usage which usually can't be erased; important for signing documents or formal papers. Please use a black pen to sign the contract. Pro Tip 3/3Artistic Expression Pens are also employed by artists for inking drawings, adding depth and permanence. The artist outlined his sketch with a fine-point pen.