"Carnegie unit" means: A standard measure of academic credit, based on the amount of time spent in class, rather than the mastery of the material, representing 120.... 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.