adj.无正式文件的，无事实证明的

There are many undocumented workers in the construction industry.
建筑行业中有很多无证工人。
The software has some undocumented features that developers discovered by accident.
这个软件有一些开发者偶然发现的未记录功能。
She lived for years in an undocumented status, afraid of being deported.
她多年来处于非法居留的状态，害怕被驱逐出境。
The undocumented immigrants often face difficulties accessing healthcare services.
无证移民往往难以获得医疗服务。
The historian had to rely on undocumented sources for part of his research.
这位历史学家不得不在部分研究中依赖未经证实的资料。
The company's financial records contained several undocumented transactions.
公司的财务记录中包含了一些未记录的交易。
The undocumented wildlife species in this region are still being studied by biologists.
生物学家们还在研究这个地区尚未记录的野生动物种类。
He was denied a job because he couldn't provide proper, undocumented proof of his qualifications.
他因为无法提供合法的、证明其资格的文件而被拒绝了工作。
Many undocumented immigrants contribute to society despite their legal status.
许多无证移民尽管他们的法律地位，但仍对社会做出贡献。
The undocumented language used by the indigenous community is at risk of being lost forever.
当地土著社区使用的未记录语言有可能永远消失。