1. ultra- - Adjective
2. ultra- - Prefix
A prefix from the Latin ultra beyond (see Ulterior), having in composition the signification beyond, on the other side, chiefly when joined with words expressing relations of place; as, ultramarine, ultramontane, ultramundane, ultratropical, etc. In other relations it has the sense of excessively, exceedingly, beyond what is common, natural, right, or proper; as, ultraconservative; ultrademocratic, ultradespotic, ultraliberal, ultraradical, etc.
Source: Webster's dictionary