potash n.

"deep, circular vessel," from late Old English pott and Old French pot "pot, container, mortar" (also in erotic senses), both from a general Low Germanic (Old Frisian pott, Middle Dutch pot) and Romanic word from Vulgar Latin *pottus, which is of uncertain origin, said by Barnhart and OED to be unconnected to Late Latin potus "drinking cup." Similar Celtic words are said to be borrowed from English and French.

Specifically as a drinking vessel from Middle English. Slang meaning "large sum of money staked on a bet" is attested from 1823; that of "aggregate stakes in a card game" is from 1847, American English.

Pot roast "meat (generally beef) cooked in a pot with little water and allowed to become brown, as if roasted," is from 1881. Pot-plant is by 1816 as "plant grown in a pot." The phrase go to pot "be ruined or wasted" (16c.) suggests cooking, perhaps meat cut up for the pot. In phrases, the pot calls the kettle black-arse (said of one who blames another for what he himself is also guilty of) is from c. 1700; shit or get off the pot is traced by Partridge to Canadian armed forces in World War II. To keep the pot boiling "provide the necessities of life" is from 1650s.

"powdery remains of fire," Middle English asshe, from Old English æsce "ash," from Proto-Germanic *askon (source also of Old Norse and Swedish aska, Old High German asca, German asche, Middle Dutch asche, Gothic azgo "ashes"), from PIE root *as- "to burn, glow." Spanish and Portuguese ascua "red-hot coal" are Germanic loan-words.

An ancient symbol of grief or repentance; hence Ash Wednesday (c. 1300), from the custom introduced by Pope Gregory the Great of sprinkling ashes on the heads of penitents on the first day of Lent. Ashes meaning "mortal remains of a person" is attested from late 13c., in reference to the ancient custom of cremation. The meaning "finely pulverized lava thrown from a volcano" is from 1660s.