staple
     adj : necessary foods or commodities; "wheat is a staple crop"
     n 1: (usually plural) a necessary commodity for which demand is
          constant [syn: {basic}]
     2: material suitable for manufacture or use or finishing [syn:
        {raw material}]
     3: a short U-shaped wire nail for securing cables
     4: paper fastener consisting of a short length of U-shaped wire
        that can fasten papers together
     v : secure or fasten with a staple or staples; "staple the
         papers together" [ant: {unstaple}]
Source: WordNet® 2.0