lettuce: [13] The lettuce was named for the milky white sap that exudes from its stalk when cut. The Latin for milk is lac (source of English lactation [17] and lactose [19]), and so the lettuce was christened lactūca. This passed into English via laituës, the plural of Old French laituë. => lactation, lactose[lettuce etymology, lettuce origin, 英语词源]