| Word | Description |
| mA | MilliAmp |
| mAH | Milliamp-hour |
| Maintenance-Free Battery | A battery that does not require water addition under normal service conditions. Both positive (+) and negative (-) grids are made of lead/calcium. |
| Marine-Cranking Amps (MCA) | A rating that is used to define the number of amps that a lead-acid marine battery at 32°F (0°C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt lead-acid battery). This artificially high rating should not be confused with CCA. |
| MCA | marine cranking amps |
| Memory Effect | A condition that is created when a NiCad or NiMH battery is partially discharged and recharged repeatedly, causing a loss of capacity. |
| MilliAmp (mA) | One one-thousandth of an amp |
| Milliamp-hour (mAH) | One one-thousandth of an amp-hour |
| Miniature Battery | A button- or coin-shaped battery — i.e., a button cell or coin cell — with a diameter greater than its height. The term miniature is also used to describe batteries made up of miniature cells. |
| Multimeter | Also known as a volt-ohm-meter (VOM), it is an instrument designed to do a variety of electrical testing, including voltage, amperage and resistance. |