Glossary
Welder Terms & Vocabulary
15 essential welder terms with plain-English definitions: the vocabulary you’ll hear in training and on day one.
Key welder vocabulary
These 15 terms come up constantly in welder training, on the job and in interviews. Knowing them helps you follow instructions, document accurately and sound prepared.
- Bead
- The deposit of weld metal along a joint.
- FCAW (flux-core)
- Flux-cored arc welding: a wire-fed process with flux in the wire.
- Fillet weld
- A triangular weld joining two surfaces at roughly right angles.
- GMAW (MIG)
- Gas metal arc welding: uses a continuously fed wire and shielding gas.
- Groove weld
- A weld made in a prepared groove between parts, often for full penetration.
- GTAW (TIG)
- Gas tungsten arc welding: precise welding with a tungsten electrode and separate filler.
- Hot work permit
- Authorization required before welding in areas with fire risk.
- Polarity (DCEP)
- Direct current electrode positive: the most common polarity for stick and MIG.
- Porosity
- Gas pockets trapped in a weld, usually from contamination or poor shielding.
- Preheat
- Heating metal before welding to reduce cracking.
- Slag
- A crust left on stick and flux-core welds that must be removed.
- SMAW (stick)
- Shielded metal arc welding: uses a flux-coated electrode; good for outdoor and repair work.
- Undercut
- A groove melted into the base metal next to the weld that isn’t filled.
- Weld positions (1G–6G)
- Codes describing joint orientation, from flat (1G) to fixed pipe at 45 degrees (6G).
- Weld puddle
- The molten metal pool the welder controls.
Practice these terms
Test yourself with the free Welder practice test: it includes vocabulary questions built from this list. For a complete course, see Welder training.
Browse terms from every career in our career glossary.