From Professor Rodman:
How did we ever get to the term “helpmate,” which [a student] has picked up from some other translation? It’s a funny history.
The King James Version reads (in 2:18) “…let us make an help meet for him,” where “meet for” is the translation of _keneged_. But “meet” in that sense became an antiquated term that people didn’t understand. Someone apparently thought it was part of a noun phrase: “help meet … for him” or “helpmeet for him.” Since that didn’t make sense to people either, they pseudo-corrected it to “helpmate for him.” And thus was born a new word in English.