Base wallah means: A person employed at a military base, or with a job far behind the front lines.. It is military jargon and mostly appears in service contexts, war fiction, or among veterans and their families. It is generally derogatory or offensive; worth a quiet word about how it lands on the person being described. 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.