Strictly speaking | LIQUID

For the physicist, liquid is the state of matter between solid and gaseous, and for nonphysicists it’s probably something to wet the whistle on a dry day. But it has long been attached to other concepts in several related verbs: liquidate, liquidise, liquefy/liquify. The oldest of these is liquidate, used since the 18th century in the financial sense of “clearing debts”, thus relating to liquidity rather than liquid itself. The more sinister sense of liquidate, “to wipe out (political opponents)”, appeared in English only during the 1920s. It probably reflects the Russian likvidirovat, the ultimate solution in the violent years of the Russian revolution. Liquidise arrived in the mid-19th century and is domesticated in an early cooking instruction: “It should be liquidised in a silver saucepan” – well before the arrival of the 20th-century kitchen liquidiser, the appliance that turns carrots to mush, if not orange fluid. Meanwhile, liquefy (or liquify) is the established verb (since the 16th century) in scientific and industrial references to turning matter in other states into liquid form. It’s there in liquefied petroleum gas (LPG), as well as in one of the most problematic effects of an earthquake, in which the ground affected by the quake liquefies. The problem of liquefaction lingers long after the aftershocks.