Meaning of ULTRA- in English

ULTRA-

ultra- /ʌltrə/ BrE AmE prefix

[ Language: Latin ; Origin: ultra 'beyond' , from ulter ; ⇨ ↑ ulterior ]

1 . extremely:

an ultra-modern building

He remained ultra-cautious.

an ultra-light jacket

2 . technical above and beyond something in a range:

ultrasound (=sound that is too high for humans to hear)

⇨ ↑ infra-

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.