from
The Collaborative International Dictionary of English v.0.48
Solder \Sol"der\, n. [Formerly soder; F. soudure, OF. soudeure,
fr. OF. & F. souder to solder, L. solidare to fasten, to make
solid. See {Solid}, and cf. {Sawder}.]
A metal or metallic alloy used when melted for uniting
adjacent metallic edges or surfaces; a metallic cement.
Hence, anything which unites or cements.
[1913 Webster]
{Hard solder}, a solder which fuses only at a red heat, as
one composed of zinc and copper, or silver and copper,
etc.
{Soft solder}, a solder fusible at comparatively low
temperatures; as, plumbers' solder, consisting of two
parts lead and one part tin, is a soft solder.
[1913 Webster]