Available Definitions:
1) a. - Sensible to slight touches; easily tickled; as, the sole of the foot is very ticklish; the hardened palm of the hand is not ticklish.
2) a. - Standing so as to be liable to totter and fall at the slightest touch; unfixed; easily affected; unstable.
3) a. - Difficult; nice; critical; as, a ticklish business.