synchronous, synchronal, synchronic -- (occurring or existing at the same time or having the same period or phase; "recovery was synchronous with therapy"- Jour.A.M.A.; "a synchronous set of clocks"; "the synchronous action of a bird's wings in flight"; "synchronous oscillations")
synchronic -- (concerned with phenomena (especially language) at a particular period without considering historical antecedents; "synchronic linguistics")
synchronic -- ((of taxa) occurring in the same period of geological time)