All the three words seem to be interchangeable and I have searched Cambridge Dictionary and Oxford Dictionaries. Oxford Dictionaries link: https://www.lexico.com/definition/nervous https://www.lexico.com/definition/anxious https://www.lexico.com/definition/fearful Cambridge Dictionary Link: https://dictionary.cambridge.org/dictionary/english/nervous?q=Nervous https://dictionary.cambridge.org/dictionary/english/anxious https://dictionary.cambridge.org/dictionary/english/fearful When can these three words and other words relating to “fear” used?Are they interchangeable?
From 1-10, nervous is the least, followed by worried then anxious being the worst. Usually, nervous is like you are scared that something would frighten you. Talking about frightened, it is about being scarier than nervous. Worried is used to describe that someone had not arrived and you are worried. Anxious, on the other hand, is like that you know something bad has happened and you are worried.