Ultimately, the answer to the question, "What is the definition of freelance work?" boils down to how the Internet has defined freelancing today.
Freelancing means that you work for yourself, and that you are contracted by companies on a project-by-project basis.
Freelancing can be trickier than taking a full-time position, but it is perfect if you're not able to devote a ton of time to the business.
If you have prior experience in an area such as marketing or accounting, freelancing may be your best work at home option.
Six-Figure Freelancing by Kelly James-Enger discusses how to make money in the field of magazine writing.