According to Longman, a contractor is "a person or company that agrees to do work or provide goods for another company", and according to Merriam Webster, it is "one that contracts to perform work or provide supplies". But does this mean that "contractor" can be used about anyone who performs any kind of job under a contract? Or, in more concrete terms: would all of the following be correctly referred to as "contractors"? If not, is there another word that would cover all of them? Would "employee" work?
A private teacher who is employed by someone to teach their kids for a fixed period of time
A lecturer at a university who is teaching a number of classes at a different uni, under a separate contract
An accountant who is temporarily hired by a company to help out with their accounting
A freelance journalist on a particular assignment
Anyone with a permanent employment