tick

tick¹

/tik/, n.

1. a slight, sharp, recurring click, tap, or beat, as of a clock.

2. Chiefly Brit. Informal. a moment or instant.

3. a small dot, mark, check, or electronic signal, as used to mark off an item on a list, serve as a reminder, or call attention to something.

4. Stock Exchange.

a. a movement in the price of a stock, bond, or option.

b. the smallest possible tick on a given exchange.

5. Manège. a jumping fault consisting of a light touch of a fence with one or more feet.

6. a small contrasting spot of color on the coat of a mammal or the feathers of a bird.

v.i.

7. to emit or produce a tick, like that of a clock.

8. to pass as with ticks of a clock: The hours ticked by.

v.t.

9. to sound or announce by a tick or ticks: The clock ticked the minutes.

10. to mark with a tick or ticks; check (usually fol. by off); to tick off the items on the memo.

11. tick off, Slang.

a. to make angry: His mistreatment of the animals really ticked me off.

b. Chiefly Brit. to scold severely: The manager will tick you off if you make another mistake.

12. what makes one tick, the motive or explanation of one's behavior: The biographer failed to show what made Herbert Hoover tick.

[1400-50; late ME tek little touch; akin to D tik a touch, pat, Norw tikka to touch or shove slightly. See TICKLE]

tick²

/tik/, n.

1. any of numerous bloodsucking arachnids of the order Acarina, including the families Ixodidae and Argasidae, somewhat larger than the related mites and having a barbed proboscis for attachment to the skin of warm-blooded vertebrates: some ticks are vectors of disease.

2. See sheeptick.

[bef. 900; ME teke, tyke, OE ticia (perh. sp. error for tiica (i.e. tica) or ticca); akin to LG tieke, G Zecke]

tick³

/tik/, n.

1. the cloth case of a mattress, pillow, etc., containing hair, feathers, or the like.

2. ticking. Also called bedtick.

[1425-75; late ME tikke, teke, tyke (c. D tijk, G Zieche) L teca, theca < Gk théke case]

tick⁴

/tik/, n. Chiefly Brit. Informal.

1. a score or account.

2. on tick, on credit or trust: We bought our telly on tick.

[1635-45; short for TICKET]

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Any of some 825 parasitic arachnid species (suborder Ixodida, order Parasitiformes), found worldwide.

Adults may be slightly more than an inch (30 mm) long, but most species are much smaller. Hard ticks start and end each developmental stage

egg, larva, nymph, adult

on the ground; at the completion of each stage, they attach to a host (usually a mammal), engorge on blood, then drop to the ground. Soft ticks feed intermittently, pass through several nymphal stages, and live in the host's den or nest. Hard ticks may draw large amounts of blood, secrete paralyzing or lethal neurotoxins, and transmit diseases. Soft ticks may also carry diseases. The deer tick is the principal vector of Lyme disease.

Cattle tick (Boophilus)

E.R. Degginger

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▪ arachnid suborder

 any of about 825 species of invertebrates (invertebrate) in the order Parasitiformes (subclass Acari (acarid)). Ticks are important parasites (parasitism) of large wild and domestic animals and are also significant as carriers of serious diseases. Although no species is primarily a human parasite, some occasionally attack humans.

      Hard ticks, such as the American dog tick (Dermacentor variabilis), attach to their hosts and feed continuously on blood for several days during each life stage. When an adult female has obtained a blood meal, she mates, drops from the host, and finds a suitable site where she lays her eggs in a mass and dies. Six-legged larvae hatch from the eggs, move up on blades of grass, and wait for a suitable host (usually a mammal) to pass by. The odour of butyric acid, emanated by all mammals, stimulates the larvae to drop onto and attach to a host. After filling themselves with the host's blood, the larvae detach and molt, becoming eight-legged nymphs. Nymphs also wait for, and board, a suitable host in the same way as larvae. After they have found a host and engorged themselves, they also fall off, and then they molt into adult males or females. Adults may wait for a host for as long as three years.

      Most hard ticks live in fields and woods, but a few, such as the brown dog tick (Rhipicephalus sanguineus), are household pests. Soft ticks differ from hard ticks by feeding intermittently, laying several batches of eggs, passing through several nymphal stages, and carrying on their developmental cycles in the home or nest of the host rather than in fields.

      Hard ticks damage the host by drawing large amounts of blood, by secreting neurotoxins (nerve poisons) that sometimes produce paralysis or death, and by transmitting diseases, including Lyme disease, Texas cattle fever, anaplasmosis, Rocky Mountain spotted fever, Q fever, tularemia, hemorrhagic fever, and a form of encephalitis. Soft ticks also are carriers of diseases.

      Adults range in size up to 30 mm (slightly more than 1 inch), but most species are 15 mm or less. They may be distinguished from their close relatives, the mites (mite), by the presence of a sensory pit (Haller's organ) on the end segment of the first of four pairs of legs. Eyes may be present or absent.

      This group has a worldwide distribution, and all species are assigned to three families: Argasidae, comprising the soft ticks, and Nuttalliellidae and Ixodidae, together comprising the hard ticks. The family Nuttalliellidae is represented by one rare African species.

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