Agequeer means: Feeling uncomfortable with one's age, imagining oneself as being a different age (often younger) than one's biological age; age dysphoria.. It is informal slang, fine in casual speech but not suited to formal contexts. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. If your teen uses it, context will usually make the intent clear. A short, curious question about where they heard it is usually all that is needed to know whether to follow up.