“拘谨的”的英语可以翻译为：overcautious，prim，restrained ...

他是个拘谨的人,不爱多说话.He is very reserved. He does not say much.我的天性是很拘谨的.I'm really a very private person.玛丽说话时脸上露出了拘谨的神色.Mary spoke with restraint in her face....