Secondary is a hold-over from wine making, where you (for reds) do a ferment on the skins and then rack it to complete the ferment. In brewing, you rack from the fermenter to a clearing (bright) tank after the ferment is complete. So, it's rare (but not unheard of) to see any fermentation in the clearing tank.
However, I don't think we will ever get rid of this confusing term.