Merriam-Webster's Collegiate® Dictionary, 11th Edition
TICK
I. noun
Etymology: Middle English tyke, teke; akin to Middle High German zeche tick, Armenian tiz
Date: 14th century
any of a superfamily (Ixodoidea) of bloodsucking acarid arachnids that are larger than the related mites, attach themselves to warm-blooded vertebrates to feed, and include important vectors of infectious diseases, any of various usually wingless parasitic dipteran flies,
II. noun see: do
Date: 15th century
the fabric case of a mattress, pillow, or bolster, ticking I,
III. noun
Etymology: Middle English tek pat, light stroke; akin to Middle High German zic light push
Date: 1680
1. a light rhythmic audible tap or beat, the time taken by the tick of a clock ; moment , a small spot or mark,
IV. verb
Date: 1721
intransitive verb to make the sound of a tick or a series of ticks, to operate as a functioning mechanism ; run , transitive verb to mark with a written tick ; check , to mark, count, or an noun ce by or as if by ticking beats , to touch with a momentary glancing blow ,
V. noun
Etymology: short for 1ticket
Date: 1642
credit , trust