an alloy (usually of lead and tin) used when melted to join two metal surfaces
"The technician applied a small amount of solder to the cracked joint before heating it until the metal flowed smoothly between the pieces."
Any of various easily-melted alloys, commonly of tin and lead, that are used to mend, coat, or join metal objects, usually small.
"The old technician carefully applied fresh solder to the cracked seam on the delicate circuit board to restore its connection."
to join items together, or to coat them with solder
"He carefully heated the two copper wires and applied a small dot of solder to permanently fuse them together."