What does aldehyde mean?
The definition of aldehyde
Al”de*hyde, n.
Etym: [Abbrev. fr. alcohol dehydrogenatum, alcohol deprived of its hydrogen.] (Chem.)

A colorless, mobile, and very volatile liquid obtained from alcohol by certain of oxidation.

Note: The aldehydes are intermediate between the alcohols and acids, and differ from the alcohols in having two less hydrogen atoms in the molecule, as common aldehyde (called also acetic aldehyde or ethyl aldehyde), C2H4O; methyl aldehyde, CH2O. Aldehyde ammonia (Chem.), a compound formed by the union of aldehyde with ammonia.