Assistant professor

Assistant professor (frequently capitalized as Assistant Professor) is an academic rank used in the United States, Canada, and some other countries. It is generally taken after earning a Master's degree or a Doctoral degree and sometimes after several years of holding a postdoctoral researcher position. It is usually below the position of associate professor and is equivalent to the rank of lecturer at most Commonwealth universities. In the United States, assistant professor is often the first position held in a tenure track, although it can also be a non-tenure track position. The title is also commonly used as the English translation of similar positions in other countries.

...
Wikipedia