Canner means: A large pot used for processing jars when preserving food, either in a boiling water bath or by capturing steam to elevate the pressure and temperature.. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. This is a food-related word and harmless in itself. 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.