Mixdown (bounce)
Rendering every track, effect and automation move into a finished audio file, usually stereo.
"Bounce" dates from the tape era, when tracks were bounced onto a spare track to free up room. A four-track machine could hold far more than four parts that way, at the cost of no longer being able to mix them separately. In DAW terms it simply means export: the mix is rendered to a WAV file that goes on to mastering.
Rendering can happen in real time, with the program playing through the song and recording its own output, or offline, computed as fast as the CPU allows. Pro Tools only did real time until version 11 in 2013, which gave a generation of engineers an involuntary coffee break per export. Real-time bouncing survives for a reason: outboard hardware in the signal path cannot be fast-forwarded.