"unspoken cold" means: The coldness that doesn't need any announcement — the level of excellence so self-evident that naming it would almost be redundant. Someone.... 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.