unlined

Etymology

un- + lined

adj

1. Without lining; without liner.
   The bitter wind made me wish I hadn't opted for that unlined coat.
   To keep constructional costs to a minimum track formations were narrower than is now customary, many tunnels were unlined, timber was largely used for bridging, and 85 lb. per yd. rails were regarded as adequate. 1941 March, “Notes and News: Modernising a Main Line”, in Railway Magazine, page 133
2. Unmarked by lines, especially of the skin.
   Even on her 70th birthday, her skin remains unlined.
   … all other classes are painted in unlined green. 1941 January, “Notes and News: Locomotive Notes”, in Railway Magazine, page 45