In this subtitle the following words have the meanings indicated. “Contract” means an agreement of any kind or nature, express or implied, for doing work or furnishing materials, or both, for or about a building. “Contract” includes an agreement for: The erection, repair, rebuilding, or improvement of a building; The drilling and installation of wells to supply water; The construction or installation of any swimming pool or fencing; The grading, filling, landscaping, and paving of the premises; The installation of waterlines, sanitary sewers, storm drains, or streets; or The erection, repair, rebuilding, or improvement of a wharf. “Contractor” means a person who has a contract with an owner. “Owner” means: The owner of the land; or An owner’s tenant for life or for years, provided the tenant enters into the contract with the contractor. “Subcontractor” means a person who has a contract with anyone except the owner or the owner’s agent. “Subcontractor” includes a supplier. “Undisputed amount” means an amount owed on a contract for which there is no good faith dispute, including any retainage withheld.