Definitions
1.NounA thin, small nail, with a slight projection at the top on one side instead of a head, or occasionally with a small domed head, similar to that of an escutcheon pin.
2.NounA paper fastener, a fastening device formed of thin, soft metal, such as shim brass, with a round head and a flat, split shank, which is spread after insertion in a hole in a stack of pages, in much the same way as a cotter pin or a split rivet.
3.VerbTo attach using a brad.
4.VerbTo upset the end of a rod inserted in a hole so as to prevent it from being pulled out, as when riveting.
5.NounA binary radian.