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Showing results for ultrasonic. Search instead for ultracold.
Definitions

ultrasonic

[uhl-truh-son-ik] / ˌʌl trəˈsɒn ɪk /
ADJECTIVE
speedy
Synonyms
STRONGEST
accelerated brisk expeditious hasty hurried immediate prompt rapid swift
WEAK
agile alacritous breakneck express fleet harefooted headlong lissome lively nimble precipitate quick-fire rapid-fire ready snappy split-second summary supersonic winged
Antonyms
STRONGEST
delayed leisurely slow sluggish
WEAK
halted slowed tardy

From Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.