This has got off to a bad start, but the answers are really almost there: WiFi and Ethernet are closely related through both the technology and the IEEE standards body that defines them.
The absolute simplest wifi-wire-to-wifi would be unscrewing both antennas on the APs and putting a length of coaxial cable between them. For short links this would probably need an attenuator, but a 1km piece of cable should attenuate quite effectively itself (-30dB maybe?). I'm not sure if the latency would prevent this from working effectively but I don't immediately see why it would.
Someone claims to have actually done this. In their case they already had the cable installed and needed to build adapters.
The "correct" solution is ethernet-over-coax or ethernet-over-fiber, but both of those require specialised conversion equipment.
You might be able to make "twinax" (twin coaxial, used for satellite TV dishes) work instead of ethernet cable with appropriate baluns, but this seems like a lot of hassle and I wouldn't try it unless the link was already there.
What will almost certainly not work is a long piece of unshielded cable, like bell wire, speaker wire, or household mains cable. You can do Ethernet over junk for short distances but not long ones.