Real Dictionary

solder
uncountable noun: Solder is the soft metal used for soldering.
verb: If you solder two pieces of metal together, you join them by melting a small piece of soft metal and putting it between them so that it holds them together after it has cooled.

solder in American English
a metal alloy that is heated and used to join or patch metal parts or surfaces: soft solders of tin-lead alloys melt easily; hard (or brazing) solders of copper-zinc alloys melt only at red heat
to become joined or united as by solder
to join, patch, etc. with solder
intransitive verb: to unite things with solder
noun: any of various alloys fused and applied to the joint between metal objects to unite them without heating the objects to the melting point
transitive verb: to join (metal objects) with solder

solder in British English
noun: an alloy for joining two metal surfaces by melting the alloy so that it forms a thin layer between the surfaces. Soft solders are alloys of lead and tin; brazing solders are alloys of copper and zinc
verb: to join or mend or be joined or mended with or as if with solder