Describing fish that migrate between salt water and fresh water; going down-stream (the opposite of anadromous).
From Greek 'kata-' (down) + 'ana-' (up) + 'dromos' (running), literally describing fish that run 'down' from freshwater to saltwater to spawn.
While 'anadromous' fish like salmon are famous for swimming upstream, catanadromous fish like eels do the opposite—they're born in the ocean and swim upstream into rivers and lakes, then swim back down to the ocean to breed.
Complete word intelligence in one call. Free tier — 50 lookups/day.