(noun)
a short, sharp beat or tap, typically occurring in a regular rhythm, similar to the sound made by a clock, or a series of such sounds;
e.g. The room was so quiet that we could hear the tick of the clock on the wall.
(noun)
(informal British) a very short period of time, a moment, figuratively the time between the beats of a clock;
e.g. I'll leave in a tick, as soon as I find my keys.
(noun)
a check mark or some other small mark, typically used to show that something from a list has been selected or dealt with or is correct, or broadly, to draw attention to something;
e.g. She put a tick mark next to each item on her shopping list as she put it in the cart.
(noun)
an arachnid that is parasitic and feeds on the blood of warm-blooded animals, often capable of transmitting diseases;
e.g. He pulled a tick out of the dog's fur.
(verb)
to make a series of short sharp noises or taps, typically in a rhythmic beat;
e.g. The watch started to tick once I put a new battery into it.
(verb)
(British) to place a check mark by an item, for example on a list or in a box on a form, to show that it has been selected, dealt with, or approved;
e.g. They were able to tick several items off their agenda before they ran out of time.