Fillet
Fillet turns up in 2 fields: adhesives, woodworking. Here is what it means to the people in each one.
Fillet in adhesives
The bead of adhesive left around the edge of a joint, which smooths stress at the ends of the bond.
A fillet is the cove of adhesive formed where squeeze-out meets the outside of the joint. Leaving a neat fillet instead of wiping it flat lowers peel stress at the overlap ends and can raise lap-joint strength noticeably. Fillets also seal the joint edge against moisture. On anaerobic and UV systems, the exposed fillet may need its own cure step.
"Don't wipe the fillet off, tool it to a nice radius, that's what's holding the edge down."
Fillet in woodworking
A small, narrow strip of wood used to fill a gap or support another component.
This slender piece of timber is typically used in stair building to fill the plow groove between balusters on a handrail or shoe rail. It spaces the spindles evenly and locks them into place. The term also applies to any very small batten or strip used for spacing, stopping, or decorative transitions in joinery.
"Cut the fillet strips to exactly four inches so our baluster spacing stays consistent."