Voortrekker means: A Boer pioneer, who trekked into the hinterland of South Africa during the 1830s.. It is mainly South African English and may not be understood outside that context. 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.