An alkali is a substance with a pH value of more than 7. Alkalis form chemical salts when they are combined with acids.
alkali in British English
(ˈælkəˌlaɪ)
nounWord forms: plural-lis or -lies
1. chemistry
a soluble base or a solution of a base
2.
a soluble mineral salt that occurs in arid soils and some natural waters
Word origin
C14: from Medieval Latin, from Arabic al-qili the ashes (of the plant saltwort)
alkali in American English
(ˈælkəˌlaɪ)
nounWord forms: pluralˈalkaˌlies or ˈalkaˌlis
1.
any base or hydroxide, as soda, potash, etc. that is soluble in water and gives a high concentration of hydroxyl ions in solution; specif., any of the hydroxides and carbonates of the alkali metals
2.
any soluble substance, as a mineral salt or mixture of salts, that can neutralize acids, has a pH greater than 7.0, and turns litmus blue: strong alkalies are caustic
Word origin
ME alkaly < Ar al-qily, for al-qili, the ashes (of saltwort) < qalai, to roast in a pan
Examples of 'alkali' in a sentence
alkali
They were approaching an area of alkali pans, where concealment was much more difficult.