A thermonuclear bomb that derives its destructive power from the fusion of isotopes of hydrogen (deuterium and tritium).
A watch (timepiece).
A heart, especially a human one.
One who makes a tick mark.
A birdwatcher who aims to see (and tick off on a list) as many bird species as possible.
A ticker tape, either the traditional paper kind or a scrolling message on a screen.
A measuring or reporting device, particularly one which makes a ticking sound as the measured events occur.