WordNet sense 1 (a contagious skin infection caused by the itch mite; characterized by persistent itching and skin irritation):

scabies

WordNet sense 2 (a strong restless desire):

urge

WordNet sense 3 (an irritating cutaneous sensation that produces a desire to scratch):

itchiness, itching

WordNet sense 4 (scrape or rub as if to relieve itching):

rub, scratch

WordNet sense 5 (have a strong desire or urge to do something):

spoil