Actually, it is 'Touch'. There is no easy way to say "Of or
pertaining to touch", so tactile became the word, and like
gubernatorial for "of and pertaining to the governer, makes no
spelling sense.
Of or pertaining to the organs, or the sense, of touch; perceiving, or perceptible, by the touch; capable of being touched; as, tactile corpuscles; tactile sensations.