1. something resembling the head of a nail that is used as an ornamental device;
2. flattened boss on the end of nail opposite to the point;
The Collaborative International Dictionary of English v.0.48:
Nail-headed \Nail"-head`ed\, a.
Having a head like that of a nail; formed so as to resemble
the head of a nail.
Nail-headed characters, arrowheaded or cuneiform
characters. See under Arrowheaded.
Nail-headed molding (Arch.), an ornament consisting of a
series of low four-sided pyramids resembling the heads of
large nails; -- called also nail-head molding, or
nail-head. It is the same as the simplest form of
dogtooth. See Dogtooth.
WordNet (r) 3.0 (2006):
n 1: something resembling the head of a nail that is used as an
2: flattened boss on the end of nail opposite to the point