- of or being the usual or standard size of a twin bed
- designating or of a bed that is 38 x 75 in
See twin-size in American Heritage Dictionary 4
- Measuring about 39 by 75 inches (99 by 190 centimeters). Used of a bed: a twin-size bed.
- Being of a size that will fit such a bed: twin-size sheets.
Origin: From twin (bed)