Thayer's Greek Lexicon

 1. to fasten one's self to, adhere to, cling to
  1) to touch
  2) of carnal intercourse with a women or cohabitation
  3) of levitical practice of having no fellowship with heathen
practices. Things not to be touched appear to be both women
and certain kinds of food, so celibacy and abstinence of
certain kinds of food and drink are recommended.
  4) to touch, assail anyone