Ab-

The prefix ab- or abs- is derived from the Latin prefix ab-, which means "off", "away", or "from" and usually expresses removing, separation, or a lower value.

According to the Oxford English Dictionary, English words beginning in ab- were originally carried directly through from Old French, as abuse, or appropriated from more modern French, as absorb.

The OED notes that in recent times, following the model of abnormal, some medical terms use ab- to mean "away from", as ab-oral, "away from the mouth".

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The prefix ab- is also used to indicate "absolute" in units used in electromagnetism, such as abhenry for inductance , abohm for resistance and abvolt for potential.