n.1. a. A generally disk-shaped fastener used to join two parts of a garment by fitting through a buttonhole or loop.
b. Such an object used for decoration.
2. Any of various objects resembling a button, especially:
a. A push-button switch.
b. The blunt tip of a fencing foil.
c. A fused metal or glass globule.
3. Computers a. In graphical user interface systems, a well-defined area within the interface that is clicked to select a command.
b. In a hypertext database, an icon that when selected allows a user to view a particular associated object.
4. Any of various knoblike structures of an organism, especially:
a. An immature, unexpanded mushroom.
b. The tip of a rattlesnake's rattle.
5. A usually round flat badge that bears a design or printed information and is typically pinned to a garment: a campaign button.
6. Informal The end of the chin, regarded as the point of impact for a punch.
7. Games a. In card games, especially poker, a plastic disk or similar marker placed in front of the person who is designated as dealer for a particular hand. At the start of each hand, the first card is dealt to the left of the button and the dealing of cards continues clockwise around the table.
b. The person who is in possession of this button.
c. The position on the gaming table where this button is located.
v.tr.1. To fasten with buttons: buttoned his shirt; buttoned up her raincoat.
2. To decorate or furnish with buttons.
3. Informal To close (the lips or mouth): Button your lip.
button up1. To fasten one's clothing tightly, as against cold weather.
2. To close or seal securely: button up the cabin for winter.
3. To complete the final details of: "Publication is a couple of months off; they're just buttoning up paperback rights" (Donald Dale Jackson).