ad hoc
formed, arranged, or done for a particular purpose only
sui generis
unique: the sui generis nature of animals.
adumbrate
report or represent in outline: James Madison adumbrated the necessity that the Senate be somewhat insulated from public passions.
• indicate faintly: the walls were not more than adumbrated by the meager light.
• foreshadow or symbolize: what qualities in Christ are adumbrated by the vine?
• overshadow: her happy reminiscences were adumbrated by consciousness of something else.