What does solder mean?
Solder is a metal alloy that melts when heated and hardens as it cools, creating a durable joint between metal parts. It is commonly used in electronics, plumbing, jewellery, and metalwork, although traditional lead-containing solder has declined in some applications because of health and environmental concerns. As a verb, solder means to use solder to join or repair metal components, as in soldering a wire to a circuit board or sealing a pipe joint. The word can also suggest making separate things into a unified whole, especially when used figuratively. Its meaning is quite specific: unlike glue, solder is designed to form a strong metallic bond through fusion, and unlike welding, it generally joins surfaces by filling the space between them rather than melting the base metals directly.
A fusible metal alloy used to join metal parts, commonly by melting it into the joint and allowing it to solidify.
"The repair required a length of solder and a hot iron."
When referring to the substance generally, solder is often treated as an uncountable noun; countable uses refer to pieces or quantities of it.
To join or fasten metal parts together by applying solder, usually with heat.
"He soldered the two copper wires to the terminal."
The verb is commonly used in electronics, plumbing, and metalworking. Figurative uses mean joining separate elements into a cohesive whole.
Used for individual pieces or quantities of solder; the material itself is normally uncountable.
"The technician tested several solders before selecting one that flowed evenly."
Solder is a metallic joining agent that turns from a soft, workable material into a solid bond—essentially making metal pieces become one.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does solder come from?
The word comes through Middle English from Old French forms such as soldure, ultimately related to Latin solidus, meaning solid. The underlying idea is of making a joint firm and solid by filling or uniting it with another metal. Modern solder developed alongside long-standing metalworking and plumbing techniques, while the verb acquired its technological sense alongside the use of fusible metal alloys in electronics and construction.
Related word forms
How solder is actually used
In technical contexts, solder usually refers to the joining material, while soldering describes the process. The term is also used figuratively in phrases such as “soldered together,” but literal metalworking is its standard meaning.
Easily confused with solder
Solder is a metal alloy or the act of joining metals, whereas a soldier is a member of an armed force.
Solder refers to joining metals, while sober means not intoxicated and can also mean serious or composed.