alka

n. [ Alkali + amide. ] (Chem.) One of a series of compounds that may be regarded as ammonia in which a part of the hydrogen has been replaced by basic, and another part by acid, atoms or radicals. [ 1913 Webster ]

{ } n. A tendency to become alkaline; or the state of a substance in which alkaline properties begin to be developed, or to predominant. Ure. [ 1913 Webster ]

a. [ Cf. F. alcalescent. ] Tending to the properties of an alkali; slightly alkaline. [ 1913 Webster ]

n.; pl. Alkalis or Alkalies [ F. alcali, ultimately fr. Ar. alqalī ashes of the plant saltwort, fr. qalay to roast in a pan, fry. ] 1. Soda ash; caustic soda, caustic potash, etc. [ 1913 Webster ]

2. (Chem.) One of a class of caustic bases, such as soda, potash, ammonia, and lithia, whose distinguishing peculiarities are solubility 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. [ 1913 Webster ]

3. Soluble mineral matter, other than common salt, contained in soils of natural waters. [ Western U. S. ] [ Webster 1913 Suppl. ]

Fixed alkalies, potash and soda. --
Vegetable alkalies. Same as Alkaloids. --
Volatile alkali, ammonia, so called in distinction from the fixed alkalies. [ 1913 Webster ]

adj. 1. having the properties of an alkali. Opposite of acidic. when used of aqueous solutions, it signifies that the solution has a pH greater than 7.
Syn. -- alkaline (vs. acidic), basic [ WordNet 1.5 ]

a. [ Cf. F. alcalifiable. ] Capable of being alkalified, or converted into an alkali. [ 1913 Webster ]

. A sterile plain, containing an excess of alkali, at the bottom of an undrained basin in an arid region; a playa. [ Webster 1913 Suppl. ]

v. i. To become changed into an alkali. [ 1913 Webster ]