| a prefix occurring originally in loanwords from Latin, with the basic meaning “on the far side of, beyond.” In relation to the base to which it is prefixed, ultra- has the senses “located beyond, on the far side of” (ultramontane; ultraviolet), “carrying to the furthest degree possible, on the fringe of” (ultraleft; ultramodern), “extremely” (ultralight); nouns to which it is added denote, in general, objects, properties, phenomena, etc., that surpass customary norms, or instruments designed to produce or deal with such things (ultramicroscope; ultrasound; ultrastructure). |
| ultra- pref.
[Latin ultrā-, from ultrā, beyond; see al-1 in Indo-European roots.] |
ultra- pref.
Beyond; on the other side of: ultraviolet.
Beyond the range, scope, or limit of: ultrasonic.