"relative majority" means: A plurality (A number of votes which is greater than the number of votes gained by any others, but which is less than a majority.).. This is a fairly neutral word with no inherent risk attached. There is no real cause for parental concern; it is descriptive vocabulary rather than something dangerous. If your child uses it, context will usually make the meaning clear. A brief, curious question about where they heard it is generally enough to know whether to follow up.