out- vs ultra-

out-

prefix
  • Greater than 

  • Toward the outside of, away from 

  • External to, on the outside of 

  • Forms verbs with the sense of surpassing or exceeding the prefixed word. This construction is productive. 

  • Completely 

  • Beyond 

ultra-

prefix
  • Greater than normal quantity or importance, as in ultrasecret. 

  • Excessively, to an extreme, as in ultramicroscopic, ultra-careful. 

  • Beyond, outside of, as in ultrasonic. 

  • intensely, extremely, or exceptional 

  • Beyond, on the far side of, as in ultraviolet. 

How often have the words out- and ultra- occurred in a corpus of books? (source: Google Ngram Viewer )