Synonymy occurs when a concept can be represented by multiple terms having the same or similar meanings. The desired content may be difficult to retrieve because it can be described by different but equivalent terminology.

Words: Artificial consciousness, Biocomputers, Electronic brains, Mechanical brains, Synthetic consciousness, Concept: Conscious automata

A controlled vocabulary must compensate for the problems caused by synonymy by ensuring that each concept is represented by a single preferred term. The vocabulary should list the other synonyms and variants as non-preferred terms with USE references to the preferred term.