Usually full time workers are understood to be those employed 35 hours a week or more–but this has now shifted. The key section of the law may be found here:
[Section 1513](4) Full-time employee
(A) In general
The term “full-time employee” means, with respect to any month, an employee who is employed on average at least 30 hours of service per week.
As Mike Sherlock notes:
…any employer in his right mind would [look at the new definition of full time worker and] reduce the hours someone worked from say 34 to something like 25 or 28, just to make sure the average hours worked was under 30.
If a lot of corporations did that, and a lot people had reduced hours, then corporations would have had to hire more workers to keep the same total number of hours.
Indeed there was a massive surge in part-time employment (+582,000) in October…
You can read the rest here and there is more there.