soda (n.) Look up soda at Dictionary.com
late 15c., "sodium carbonate," an alkaline substance extracted from certain ashes (now made artificially), from Italian sida (or Medieval Latin soda) "a kind of saltwort," from which soda is obtained, perhaps from Arabic suwwad, the name of a variety of saltwort exported from North Africa to Sicily in the Middle Ages, related to sawad "black," the color of the plant.

Washing soda (sodium carbonate) is commonly distinguished from baking soda (sodium bicarbonate). The meaning "carbonated water" is first recorded 1834, a shortening of soda water (1802). Soda fountain is from 1824; soda jerk first attested 1883. First record of soda pop is from 1873.