Vitamin A deficiency: Related Medical Conditions. To research the causes of Vitamin A deficiency, consider researching the causes of these these diseases that may be similar, or associated with Vitamin A deficiency:
Definition of push button. : a small button or knob that when pushed operates something especially by closing an electric circuit.
Before the introduction of touch-tone telephone sets, the Bell System sometimes used the term push-button telephone to refer to key system telephones, which were rotary dial telephones that also had a set of push-buttons to select one of multiple telephone circuits, or to activate other features.