Mint
Undistinguishable from new, original in every way.  May be in factory box, with papers.  May have been in showcase or used in display, or bought new and never worn, or worn so little as to show no wear whatsoever, or in rare cases restored to perfection.

Near mint
Completely original in every way. Faint marks or light scratches may be observed under magnification. May have been expertly restored, repaired or serviced.

Excellent
Looks as  though watch was used very little if at all. If watch has been  restored, all original replacement parts have been used. Faint scratches are evident but hard to detect with the eye. No dents are detectable and the bracelets have little or no wear.

Very good
The watch will show some wear, and perhaps is in need of some routine servicing, but a sound attractive presentation overall. No evidence of abuse. May have new hands and new crystal, but original case and movement. Dial may have been restored or need refinishing but the overall appearance is acceptable.

Good
Nothing fundamentally wrong with the watch, though it has obviously been used. Movement may have had a part replaced, but the part was near to original. Possibly in need of a servicing and restoration or buffing of the case or bracelet, due to nicks and mars or more noticeable scratches. Runs well but may need timing adjustments or service for optimal performance.

Fair
Well used, possibly in need of a servicing and restoration.  May be running erratic.  May not have original dial or case. Even an untrained eye could tell the watch has seen better days, but overall still wearable and worthy of consideration.

Poor
Anybody's guess as to whether it can ever made to run again. Speculative piece and should be priced accordingly. Maybe 'fixer-upper' would be too generous a term.