Generally accepted short form of locum teneus, or short term substitute for an IFA in the event of absence from work for any reason e.g. holiday, sickness. The locum must be able to provide the same level of advice as the principal.
A Locum is a person who fulfills the duties of another. For example, a Locum doctor is a doctor who works in the place of the regular doctor when that doctor is on holiday or ill.