Nectar was a type of beverage. This sweet beverage was made from the secretions of a plant's flowers. In the mythology of the ancient Greeks and Romans, nectar was consumed by their deities.
In 2270, while on Taurus II, the Taurians offered nectar to James T. Kirk, Spock, and Leonard McCoy. McCoy felt the nectar was more potent than Saurian brandy. After drinking the nectar, the men went into a deep slumber. (TAS: "The Lorelei Signal")