c.1616, "pool or lake for irrigation or drinking water," a word originally brought by the Portuguese from India, ult. from Gujarati
tankh "cistern, underground reservoir for water," Marathi
tanken, or
tanka "reservoir of water, tank." Perhaps from Skt.
tadaga-m "pond, lake pool," and reinforced in later sense of "large artificial container for liquid" (1690) by Port.
tanque "reservoir," from
estancar "hold back a current of water," from V.L.
*stanticare (see
stanch). But others say the Port. word is the source of the Indian ones. Meaning "fuel container" is recorded from 1902. Military use originated 1915, partly as a code word, partly because they looked like benzene tanks. They were first used in action at Pozieres ridge, on the Western Front, Sept. 15, 1916. Slang meaning "detention cell" is from 1912.
Tanker "ship for carrying oil or other liquid cargo," is first attested 1900.
Tank top is 1968, from
tank suit "one-piece bathing costume" (1920s), so called because it was worn in a swimming
tank, or pool.