hydrous

IPA/ˈhaɪ.drəs/
KK[hˈaɪdrəs]IPA/ˈhaɪ.drəs/

hydrous — adjective

  • hydrouspositive
  • more hydrouscomparative
  • most hydroussuperlative

1. describes a substance whose molecules include water that is chemically attached

1.adjectiveC1
Definition

describes a substance whose molecules include water that is chemically attached to them — not just water on the surface, but water locked inside the crystal or molecular structure, such as in certain minerals or compounds

Example

Keiko heated the blue hydrous copper sulfate crystals until they turned white and powdery.

hydrous + copper sulfate — a common school chemistry example

Gypsum is a soft hydrous mineral that forms when seawater evaporates in hot climates.

common hydrous mineral: gypsum

Common collocations
  • hydrous mineral
  • hydrous compound
  • hydrous oxide
  • hydrous clay
  • hydrous conditions
  • hydrous phase
Synonyms
  • hydrated

    more common in everyday chemistry; 'hydrated' also describes water added to a compound, while 'hydrous' is mostly used in geology and mineralogy

Antonyms
  • anhydrous

    the direct opposite — describes a substance that contains no chemically bonded water, e.g. anhydrous ammonia

Grammar Patterns

hydrous + noun

Usage Note

Primarily a technical term in chemistry, geology, and materials science. The opposite is 'anhydrous', which describes a substance with no chemically combined water. Do not confuse with 'wet' or 'moist', which describe surface water only.

Common Mistakes

The towel is hydrous after washing it.
The towel is wet after washing it.
'hydrous' means water is chemically bonded, not just on the surface.
Hydrous cement is mixed with water to build walls.
Hydrous minerals contain water in their crystal structure.
It is not a synonym for 'mixed with water' or 'wet'.

Word family

Synonym discussion

Sense: adjective/1

'Hydrous', 'hydrated', and 'aqueous' all relate to water, but they are used in different contexts. 'Hydrous' is the most specific: it describes a solid substance whose crystal structure contains chemically bonded water — a concept central to mineralogy and inorganic chemistry. 'Hydrated' is broader and more common in everyday chemistry; a hydrated compound is one that has taken up water, often through a chemical reaction (e.g., hydrated lime). 'Aqueous' refers to something dissolved in or related to water as a solvent — for example, an aqueous solution is simply a mixture where water is the liquid, regardless of chemical bonding. To compare: hydrous copper sulfate has water inside its crystals; hydrated cement has reacted with water to harden; an aqueous salt solution has salt dissolved in water.

hydrous ↗hydrated ↗aqueous ↗

Common collocations

Nouns

Phrases

  • hydrous mineral deposits
  • hydrous alteration zone
  • hydrous melting conditions

Etymology

GreekEnglish

From the Greek word 'hydōr' (meaning 'water'), combined with the suffix '-ous', which means 'full of' or 'containing'. The term entered scientific English in the early 1800s as chemists began to describe the water content locked inside the crystal structure of minerals and salts.