noun
USO
noun
1
An unidentified object seen underwater, whether submerged or partly submerged.
"The sonar operator logged an uso off the coast that was never explained."
How to Use USO
Learner’s notesIn plain EnglishBasically the underwater version of a UFO sighting.
Easily confused with
Word Forms
USOs plural
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The sonar operator logged an _____ off the coast that was never explained.
Etymology
An initialism built the same way as "UFO," standing for "unidentified submerged/submarine object."