A teetotaler was an individual who practiced a strict form of temperance in abstaining from alcoholic beverages.
When asked if he would like something to drink by the Species 8472 Valerie Archer replicant, Commander Chakotay asked for water, prompting Archer to ask if Chakotay was a teetotaler. Chakotay responded that he liked to remain in control. (VOY: "In the Flesh")