As used in this part, the term:

(1) "Contractor" means a contractor having privity of contract with the owner of the real estate.

(2) "Land surveyor" means the same as the definition thereof in Code Section 43-15-2.

(3) "Materials," in addition to including those items for which liens are already permitted under this part, means tools, appliances, machinery, or equipment used in making improvements to the real estate, to the extent of the reasonable value or the contracted rental price, whichever is greater, of such tools, appliances, machinery, or equipment.

(4) "Materialmen" means all persons furnishing the materials, tools, appliances, machinery, or equipment included in the definition of materials in paragraph (3) of this Code section.

(5) "Professional engineer" means the same as the definition thereof in Code Section 43-15-2.

(6) "Registered forester" means the same as the definition of such term in Code Section 12-6-41.

(7) "Registered land surveyors" and "registered professional engineers" means land surveyors or professional engineers who are registered as land surveyors or professional engineers under Chapter 15 of Title 43 at the time of performing, rendering, or furnishing services protected under this part.

(8) "Residential property" means single-family and two-family, three-family, and four-family residential real estate.

(9) "Subcontractor" means, but is not limited to, subcontractors having privity of contract with the contractor.