Not simultaneous; not concurrent in time; -- opposed to synchronous. [Webster 1913 Suppl.]
occurring in different geologic times; -- of taxa/ [WordNet 1.5]
chronologically misplaced; belonging to a different time or era [WordNet 1.5]
occurring at different speeds in different computers connected by a data transmission link; -- said of methods data of transmission between computers. Opposite of synchronous. [PJC]