1. Very short.
- ultrashort skirts
2. (sciences) Extremely short in duration, typically on the femtosecond scale
- an ultrashort pulse
3. (physics, of a wave) Having a wavelength of between 1 and 10 metres
4. (finance) Having a very short term of investment, typically less than a year
- an ultrashort bond
1. (finance) A bond with an extremely short term, typically less than a year