Merriam-Webster Collegiate Dictionary - addict

 I. transitive verb  Etymology: Latin ~us, past participle of addicere to favor, from ad- + dicere to say — more at diction  Date: 1534  1. to devote or surrender (oneself) to something habitually or obsessively ~ed to gambling  2. to cause ~ion to a substance in (a person or animal)  II. noun  Date: 1909  1. one who is ~ed especially to a substance  2. devotee a detective novel ~