"Outboard gear" is HARDWARE-based signal processing equipment that resides outside of the mixing console and/or the recording medium. This includes gear like: EQ's, mic pre's, dynamics processing (compressors,gates.etc), effects processors (reverbs, delays, etc), converters (A/D, D/A), headphone amps, sub-mixers, et al. All of the stuff you see racked-up in a studio is basically "outboard gear". The "Anti-Outboard" would be software plug-ins, which is software-based processing that resides WITHIN the recording/mixing medium. Does that help?

Outboard started as gear that was "out of the mixing board" like dedicated mic preamps, eq's compressors, gates and effects. Now days it means more of almost anything that is not software, or just about any gear that can be rack mounted.

It started when people would have a preference in using some other hardware gear, or gear that was in addition to the recording/mixing board that was used for the recording and mixing.

yes, that helps thanks alot!