ultrashort

[ uhl-truh-shawrt ]
/ ˌʌl trəˈʃɔrt /

adjective

extremely short.
(of a wavelength) smaller than 10 meters.

Origin of ultrashort

First recorded in 1925–30; ultra- + short
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for ultrashort

ultrashort

/ (ˌʌltrəˈʃɔːt) /

adjective

(of a radio wave) having a wavelength shorter than 10 metres

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012