11B

11B means: An infantryman.. It is military jargon and mostly appears in service contexts, war fiction, or among veterans and their families. 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.

11B means: An infantryman.. Register: informal, military jargon. Suitable only for casual conversation, chat and social media. Do not use in business, academic or news writing. Common learner mistake is using the word in a register it does not fit, or assuming a single global meaning; always check the context before producing it yourself. A formal-English equivalent (a synonym or descriptive phrase) is usually safer in writing. When in doubt, paraphrase rather than reuse the slang form.