a food constituting the main nourishment of a community, etc
the main constituent of something
that train of meteorological questions and answers which forms the great staple of polite English conversation — Sidney Smith
the main trading commodity or raw material of a region
the fibre of cotton or wool graded for length and fineness
wool of a short staple
in the Middle Ages, a town appointed, usu by royal authority, to be the centre for merchants involved in the sale or export of commodities in bulk
[Middle English from Old French estaple market, from early Dutch and early Low German stapel emporium, pillar]