1) Spike brad-shaped 2) Timber spike 
• (n.) A peculiar brad-shaped spike, to be driven alongside the end of an abutting timber to prevent its slipping.
Brob noun [ Confer Gael. brog , English brog , noun ] (Carp.) A peculiar brad-shaped spike, to be driven alongside the end of an abutting timber to prevent its slipping. 
a wedge-shaped spike for securing an end of a timber butting against the side of another.