1540s (early 15c. as alcofol), "fine powder produced by sublimation," from Medieval Latin alcohol "powdered ore of antimony," from Arabic al-kuhul "kohl," the fine metallic powder used to darken the eyelids, from kahala "to stain, paint." The al- is the Arabic definite article, "the."
Paracelsus (1493-1541) used the word to refer to a fine powder but also a volatile liquid. By 1670s it was being used in English for "any sublimated substance, the pure spirit of anything," including liquids. Sense of "intoxicating ingredient in strong liquor" is first recorded 1753, short for alcohol of wine, which was extended to "the intoxicating element in fermented liquors." In organic chemistry, the word was extended 1850 to the class of compounds of the same type as this.