a. [f. VALVE sb.] Having no valve; destitute or devoid of valves.
1830. Lindley, Nat. Syst. Bot., 219. Capsule … sometimes valveless, or dehiscing transversely.
1851. Woodward, Mollusca (1856), 69. Animal and pen like Loligo in most respects;… funnel valveless.
1881. Mivart, Cat, 216. The hepatic veins are valveless.
1884. Knight, Dict. Mech., Suppl. 919. The ‘Wardwell’ valveless engine … is horizontal.
