Tickle \Tic"kle\, v. t. [imp. & p. p. Tickled; p. pr. & vb. n. Tickling.]

[Perhaps freq. of tick to beat; pat; but cf. also AS. citelian to tickle, D. kittelen, G. kitzlen, OHG. chizzil[=o]n, chuzzil[=o]n, Icel. kitla. Cf. Kittle, v. t.]

1. To touch lightly, so as to produce a peculiar thrilling sensation, which commonly causes laughter, and a kind of spasm which become dengerous if too long protracted.

If you tickle us, do we not laugh? --Shak.

2. To please; to gratify; to make joyous.

Pleased with a rattle, tickled with a straw. --Pope.

Such a nature Tickled with good success, disdains the shadow Which he treads on at noon. --Shak.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Tickle \Tic"kle\, v. i.

1. To feel titillation.

He with secret joy therefore Did tickle inwardly in every vein. --Spenser.

2. To excite the sensation of titillation. --Shak.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Tickle \Tic"kle\, a.

1. Ticklish; easily tickled. [Obs.]

2. Liable to change; uncertain; inconstant. [Obs.]

The world is now full tickle, sikerly. --Chaucer.

So tickle is the state of earthy things. --Spenser.

3. Wavering, or liable to waver and fall at the slightest touch; unstable; easily overthrown. [Obs.]

Thy head stands so tickle on thy shoulders, that a milkmaid, if she be in love, may sigh it off. --Shak.

Source: Webster's Revised Unabridged Dictionary (1913)