ultrashort

adj

1. (informal, not-comparable)Very short.

   “ultrashort skirts”

2. (not-comparable)Extremely short in duration, typically on the femtosecond scale

   “an ultrashort pulse”

3. (not-comparable)Having a wavelength of between 1 and 10 metres
4. (not-comparable)Having a very short term of investment, typically less than a year

   “an ultrashort bond”

noun

1. A bond with an extremely short term, typically less than a year

   “Ultrashorts were a way for the fund industry to appeal to bank customers, by offering an investment whose price did not vary much but whose yield was higher than that on certificates of deposit.”