1) Aldehyde 2) Ethanal trimer 
Paraldehyde is the cyclic trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane. The corresponding tetramer is metaldehyde. A colourless liquid, it is sparingly soluble in water and highly soluble in alcohol. Paraldehyde slowly oxidizes in air, turning brown and producing an odour of acetic acid. It quickly reacts with m...
• (n.) A polymeric modification of aldehyde obtained as a white crystalline substance.
colourless liquid of disagreeable taste and pungent odour used in medicine as a sedative–hypnotic drug and in chemistry in the manufacture of organic ...
(par-al´dә-hīd) a sedative and hypnotic; because of its low therapeutic index and certain unpleasant side effects, its use has declined in recent years.
Par·al'de·hyde noun [ Prefix para- + aldehyde .] (Chemistry) A polymeric modification of aldehyde obtained as a white crystalline substance. 
Type: Term Pronunciation: par-al′dĕ-hīd Definitions: 1. A cyclic polymer of acetaldehyde; a potent hypnotic and sedative, suitable for oral or rectal administration; its offensive odor limits its use. Synonyms: paracetaldehyde
[n] - a colorless liquid (a cyclic trimer of acetaldehyde) that is used as a sedative and a solvent
ethanal trimer noun a colorless liquid (a cyclic trimer of acetaldehyde) that is used as a sedative and a solvent