For purposes of this act:
"Employer" means a partnership, association, joint stock company, trust, corporation, or other legal business entity or successor thereof who is primarily engaged in the business of, or enters into a contract for, making improvements to real property and includes any subcontractor or lower tier contractor.
"Public body" means the State of New Jersey, any of its political subdivisions, any authority created by the Legislature of the State of New Jersey and any instrumentality or agency of the State of New Jersey or of any of its political subdivisions.
"Public work" means construction, reconstruction, demolition, alteration, custom fabrication, or repair work, or maintenance work, including painting and decorating, done under contract and paid for in whole or in part out of the funds of a public body, except work performed under a rehabilitation program. "Public work" shall also mean construction, reconstruction, demolition, alteration, custom fabrication, or repair work, done on any property or premises, whether or not the work is paid for from public funds, if, at the time of the entering into of the contract:
N.J.S. § 34:20-3