The English suffixes -phobia, -phobic, -phobe (of Greek origin) occur in technical usage in psychiatry to construct words that describe irrational, disabling fear as a mental disorder (e.g., agoraphobia), in chemistry to describe chemical aversions (e.g., hydrophobic), in biology to describe organisms that dislike certain conditions (e.g., acidophobia), and in medicine to describe hypersensitivity to a stimulus, usually sensory (e.g., photophobia). In common usage they also form words that describe dislike or hatred of a particular thing or subject.