Frog
An indentation within a brick which reduces weight.
The frog face of the brick is normally laid face up for maximum strength.
Frottage
Frottage 
A texture pattern achieved by overlaying a wet coat of glaze with lining paper crumpled to provide creases and folded areas.
Galvanised Steel
Galvanised steel is where steelwork is dipped coated with zinc.
See: Galvanised process: https://www.galvanizing.org.uk/galvanizing-process/
Gargoyles
In architecture, a formed grotesque fixture with a spout designed to convey water from a roof and away from the side of a building, thereby preventing it from running down masonry walls and eroding the mortar.
Garnet Paper
As glass paper but with a more hard wearing abrasive surface which produces a smoother wood finish then standard glass paper
glass.
ibre Reinforced Concrete.