Definition of "Tick" :

noun: any of two families of small parasitic arachnids with barbed proboscis; feed on blood of warm-blooded animals

noun: a light mattress

noun: a mark indicating that something has been noted or completed etc.

noun: a metallic tapping sound

"He counted the ticks of the clock."

verb: put a check mark on or near or next to

"Tick off the items."

verb: sew

"Tick a mattress."

verb: make a sound like a clock or a timer

"The clocks were ticking."

verb: make a clicking or ticking sound

"The clock ticked away."