Flounders are fish, members of the flatfish family. Flatfish are known principally for two things:
- being flat
- living on the “bottom“ of the sea.
The Latin “fundus” means “bottom” (which also gives us the words “foundation,” “found” and “fundamental,” among others).
This has always seemed like a relatively obvious connection to me - found/flounder - yet another thread on stackexchange is entertaining much less likely connections.
For example, virtually ALL fish flop around when placed on the deck of a boat, not just members of the flounder family.