See Also: entrance block(medicine)
Entrance(medicine)
entrance(2)(dictionary)
entrance(1)(dictionary)
entrance 2, verb(dictionary)
entrance 1, noun(dictionary)
entrance pupil(medicine)
Common Entrance Examination, the(dictionary)
Service Entrance Deli(tourism)
Entrance Fee - Horse Racing(gambling)

third 2, noun (oh) and entrance block (medicine)


third 2, noun (oh)



2 n [C]
one of three equal parts of something
::Divide it into thirds.
third of
:: A third of these Jobs are held by women.
one-third/two-thirds
::Two-thirds of the profits are given to charities.
the lowest type of degree that is given by a British university

entrance block (medicine)


entrance block -->
protective block


An incompletely understood mechanism whereby a pacemaker is protected from being discharged by the impulse from another centre; the mechanism, usually conceived as an encircling zone of unidirectionally refractory tissue permitting egress of impulses from the centre but preventing access to the centre, is seen in operation in ventricular parasystole where the parasystolic centre is protected from discharge by the sinus pacemaker and so is able to maintain its intrinsic rhythm undisturbed.

Synonym: entrance block, protection.