the word "tarmac" is a portmanteau and proprietary name originating in the early 20th century. it combines "tar," a substance known since old english times from proto-germanic origins, with a truncation of "macadam," the surname of john loudon mcadam. his method involved compacting layers of crushed stone, which was later improved by adding tar as a binding agent to create a smoother, dust-free surface. thus, "tarmac" logically evolved from a specific brand name for this tar-bound macadam into a generic term for paved airport and road surfaces.

Structure: tar + mac tar (old english, a dark, thick, flammable liquid); mac (shortened form of macadam, from the surname of john l. mcadam, a scottish engineer who pioneered a method of road construction).