In plain English
This means there is only one size choice for the clothing item. It is an apparel size label that shows the item does not come in several sizes.
In context
Here, "One size" communicates that the item is offered in a single size option.
- Situation
- Browsing product availability, variants, stock, condition, and seller information
- What it communicates
- labels the item as offered in a single size option.
Meaning limits
By itself, the term does not say whether that single size will fit any particular person.
Examples
“The cap comes in one size, but the coat is available in four.”
“The poncho was marked one size, so there was nothing else to choose from.”