Adjective
valveless (not comparable)
Having no valves.
Many traditional conservatories and players refused to use them at first, claiming that the valveless horn, or natural horn, was a better instrument. Source: Internet
The Thebesian veins within the myocardium of the heart are valveless veins that drain directly into the chambers of the heart. Source: Internet
Ink jet printers operating on the Piezoelectric transducer principle also use valveless pumping. Source: Internet
Pumps can be classified by their method of displacement into positive displacement pumps, impulse pumps, velocity pumps, gravity pumps, steam pumps and valveless pumps. Source: Internet
The fluid pumping efficiency of a valveless system, however, is not necessarily lower than that having valves. Source: Internet