sur- vs ultra-

sur-

prefix
  • A syncopic variant of super-. 

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 sur- and ultra- occurred in a corpus of books? (source: Google Ngram Viewer )