The Eleventh Doctor enjoyed denoting various things as cool, such as fezes, (TV: The Big Bang) stetsons (TV: Day of the Moon [+]Loading...["Day of the Moon (TV story)"]) shrubbery, (PROSE: Hello! [+]Loading...["Hello! (short story)"]) and, most prominently, bow ties. (TV: The Eleventh Hour [+]Loading...["The Eleventh Hour (TV story)"], The Snowmen [+]Loading...["The Snowmen (TV story)"], etc al.) He told himself to "be cool" when making a first impression to Clara Oswald. (TV: The Bells of Saint John [+]Loading...["The Bells of Saint John (TV story)"], The History of the Doctor [+]Loading...["The History of the Doctor (TV story)"])
The Twelfth Doctor cited the Eleventh Doctor's usage of the world "cool", among other reasons, as to why he held a low opinion of his predecessor. (COMIC: Terrorformer [+]Loading...["Terrorformer (comic story)"]) During a Multi-Doctor event, the Eleventh Doctor came to think of his successor as "very cool" if he had retained Clara as a companion. (COMIC: Four Doctors [+]Loading...["Four Doctors (comic story)"])
The Fifteenth Doctor's "distinguishing features" included a "very cool moustache". (PROSE: Who's the Doctor? [+]Loading...{"page":"7","1":"Who's the Doctor? (short story)"})