A cloaking frequency printed in frosting on a cake
A cloaking frequency was a specific energy modulation used by species with cloaking technology. Cloaking frequencies were a rough pattern, as one was accurately drawn on a pistachio cake using a parra creme sauce.
In 2376, Tuvok was able to provide Captain Janeway with the cloaking frequency used by a mysterious Delta Quadrant species known as the "Ba'Neth", allowing Voyager to penetrate the Ba'neth's cloaks. (VOY: "Riddles")