cute as a button

Pleasing in appearance or temperament. This phrase is most often applied to children and females. Your little girl is as cute as a button in that frilly dress. Katie is pretty and has such a sweet disposition—she's as cute as a button.

Also, cute as a bug's ear. Pretty or attractive in a dainty way, as in That baby is cute as a button. Cute originally was a shortening of acute, for "sharp-witted and clever," but in the early 1800s it also took on its current meaning. Other than that buttons and bug's hearing organs can be small, there is no good explanation for these similes.

Daintily attractive. The word “cute” dates from the seventeenth century. It was originally an abbreviation of acute and had the same meaning: clever, shrewd, ingenious. In America, however, it came to be applied to attractive persons or things, those with an appearance of dainty charm rather than outright beauty. A button is small and round; so are some cute objects. For some reason this simile took hold in the early twentieth century. The synonym cute as a bug’s ear similarly alludes to something very small—and in fact nonexistent (bugs don’t have ears).