Definition of "landline"

landline

noun
plural landlines
1. A fixed telephone communications cable; originally, one run over land, as opposed to a submarine cable.
  Quotations
  The land line was eight months later in its completion than was anticipated, but the fleet of cable ships, sent out by the British Australian Telegraph Company, arrived in Port Darwin at the date appointed by them: November 6th, 1871.
  1887, Harriet W. Daly, Digging, Squatting, and Pioneering Life in the Northern Territory of South Australia, page 134
2. (by extension) A telephone connected by such a fixed wire, specifically not wireless/mobile.
3. (attributively) That which is connected by such a fixed wire (telephone, internet etc.).