A decoy in an auction- room; so called because he buttons or
ties the unwary to bargains offered for sale. The button fastens or
fixes what else would slip away.
The button of the cap.
The tip-top. Thus, in Hamlet,
Guildenstern says: “On
fortune's cap we are not the very button” (act ii. sc. 2), i.e.
the most highly favoured. The button on the cap was a mark of honour.
Thus, in China to the present hour, the first grade of literary honour
is the privilege of adding a gold button to the cap, a custom adopted
in several collegiate schools of England. This gives the expression
quoted a further force. Also, the several grades of mandarins are
distinguished by a different coloured button on the top of their cap.
Button (of a foil).
The piece of cork fixed to the end of a foil to protect the point
and prevent injury in fencing.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894