"Clydesdale" means: A heavier than usual athlete (Over 200 lbs for men, over 145 lbs for women).. 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.