Definition

1. Adjective:
   • Without water; especially without water of crystallization: Describes a substance, particularly a chemical compound, from which all water molecules have been removed. This is a specific scientific term, most commonly used in chemistry to refer to salts or other compounds that do not contain water molecules integrated into their crystalline structure.

Usage Examples

• Adjective:
  • The chemist prepared an anhydrous form of the salt for the experiment.
  • This reaction requires the use of anhydrous ethanol as a solvent.
  • The anhydrous compound is highly hygroscopic, meaning it readily absorbs moisture from the air.

Advanced Usage

• Technical Context: The term is almost exclusively used in scientific and industrial contexts (chemistry, pharmacy, materials science) to specify the purity or state of a substance.
  • The laboratory procedure mandates anhydrous conditions to prevent side reactions with water.
• "Anhydrous ammonia": A specific industrial term for ammonia gas (NH₃) that is not dissolved in water, used primarily as a fertilizer.
  • Farmers use anhydrous ammonia to provide nitrogen to crops.

Variants and Related Words

• Anhydride (noun): A compound formed by the removal of water from another compound, often an acid.
  • Acetic anhydride is a common reagent in organic synthesis.
• Dehydrate (verb): To remove water from a substance, often used in broader contexts (e.g., food, the body).
  • You can dehydrate fruits to preserve them.

Synonyms

• Dry: Lacking moisture. (Note: "Dry" is a general term, while "anhydrous" is a precise scientific term implying the complete absence of water, especially water of hydration.)
• Water-free: A more descriptive, less technical synonym.

Antonyms

• Hydrated: Containing water, especially water chemically combined with a substance.
• Aqueous: Dissolved in or involving water.

Adjective

1. without water; especially without water of crystallization