Quarrelous means: An adjective meaning prone to arguing - a regional or older variant of 'quarrelsome' used mainly in American English or older texts. Applied to a person with a combative, contentious disposition. There is no real cause for parental concern; it is descriptive vocabulary rather than risky behaviour. As a place or proper-name reference it is purely descriptive. 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.