arc - auxi
- arch-shaped roof
- arch-type steam hammer
- arched-type piling bar
- arcing
- arcing process
- arcing time factor
- arcing voltage
- arcm, arl ar3, ar4, ar
- Arco microknife
- arcs of powder pattern
- Ardal
- ardometer
- area of cup
- area of indentation
- argentometer
- argillaceous gangue
- argillaceous ore
- argillaceous siderite
- argon
- argon arc