1. From, away from, off.
2. Prefix applied to electrical units in the CGS-electromagnetic system to distinguish them from units in the CGS-electrostatic system (prefix stat-) and those in the metric system or SI (no prefix).
The information shown above for ab- is provided by Stedman's.
* Stedman's, part of Lippincott Williams & Wilkins, provide a comprehensive line of health-science publications for healthcare professionals and medical students.