| 1. | a small disk, knob, or the like for sewing or otherwise attaching to an article, as of clothing, serving as a fastening when passed through a buttonhole or loop. |
| 2. | anything resembling a button, esp. in being small and round, as any of various candies, ornaments, tags, identification badges, reflectors, markers, etc. |
| 3. | a badge or emblem bearing a name, slogan, identifying figure, etc., for wear on the lapel, dress, etc.: campaign buttons. |
| 4. | any small knob or disk pressed to activate an electric circuit, release a spring, or otherwise operate or open a machine, small door, toy, etc. |
| 5. | Botany. a bud or other protuberant part of a plant. |
| 6. | Mycology.
|
| 7. | Zoology. any of various small parts or structures resembling a button, as the rattle at the tip of the tail in a very young rattlesnake. |
| 8. | Boxing Informal. the point of the chin. |
| 9. | Also called turn button. a fastener for a door, window, etc., having two arms and rotating on a pivot that is attached to the frame. |
| 10. | Metallurgy. (in assaying) a small globule or lump of metal at the bottom of a crucible after fusion. |
| 11. | Fencing. the protective, blunting knob fixed to the point of a foil. |
| 12. | Horology. crown (def. 19). |
| 13. | Computers. (in a graphical user interface) any of the small, labeled areas upon which the user can click with a mouse to choose an option. |
| 14. | to fasten with a button or buttons: She quickly buttoned her coat. |
| 15. | to insert (a button) in a buttonhole or loop: He buttoned the top button of his shirt. |
| 16. | to provide (something) with a button or buttons. |
| 17. | to be capable of being buttoned: This coat buttons, but that one zips. |
| 18. | button up, Informal.
|
| 19. | have all one's buttons, Informal. to be mentally competent, alert, and sane; have all one's wits: At 106 she still has all her buttons. |
| 20. | on the button, Informal. exactly as desired, expected, specified, etc.: The prediction for snow was right on the button. |

button
|
|
on the button
and on the bean
|
button but·ton (bŭt'n)
n.
A knob-like structure, device, or lesion.
on the button
Exactly right, precisely, as in Her review of the book was right on the button, or We're supposed to be there at six o'clock on the button. This term may come from boxing, where a punch on the button means "a punch on the chin." [Colloquial; c. 1900] Also see on the dot.