Edit
A jacket that is naturally designed with a low and wide-cut neckline, not covering the shoulders or upper chest area, leaving them bare.
In regards to the tag usage on Danbooru, compared to other specific "off-shoulder" tags, this tag is very infamous for being frequently misused among the userbase for open or partially-open jackets that are worn hanging off the upper arms, regardless of how they were designed to be worn.
If unsure whether or not the clothing in question qualifies as an off-shoulder jacket, use the off shoulder tag instead.
See also
- Off-shoulder coat (another frequently misused "off-shoulder" tag)
- List of commonly misused tags
- Off shoulder
- Off-shoulder dress
- Off-shoulder shirt
- Off-shoulder sweater
- Off-shoulder one-piece swimsuit
This tag implicates off_shoulder (learn more).