| 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.
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| 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.
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| 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
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button but·ton (bŭt'n)
n.
A knob-like structure, device, or lesion.