alk.

Adjective

alkaline (comparative more alkaline, superlative most alkaline)

1. Of, or relating to an alkali, one of a class of caustic bases.
   • [Joseph Black's] experiments on magnesia alba, quick lime, and other alkaline substances proved that "fixed air" is given off when limestone is burned, and that the same loss is incurred when it is dissolved in muriatic acid (hydrochloric acid).1913, James Campbell Brown, A History of Chemistry from the Earliest Times, page 279
2. Having a pH greater than 7.

   Synonyms:

   basic

See all 3 meanings of alkaline

Noun

alkali (countable and uncountable, plural alkalis or alkalies)

1. One of a class of caustic bases, such as soda, soda ash, caustic soda, potash, ammonia, and lithia, whose distinguishing characteristics are dissolving in alcohol and water, uniting with oils and fats to form soap, neutralizing and forming salts with acids, turning to brown several vegetable yellows, and changing reddened litmus to blue.
   • Alkalies may be defined as bodies which combine with acids so as to impair or neutralize their activity, and produce what are called salts. They are distinguished by properties the reverse of acids, and the two classes are generally looked upon as antagonist substances.1846, editorial staff, “CHEMISTRY”, in Scientific American, series 1, Volume 2, Issue 13, page 102
2. (US, Western) Soluble mineral matter, other than common salt, contained in soils of natural waters.