Noun
The third above the keynote; -- so called because it divides the interval between the tonic and dominant into two thirds.
Source: Webster's dictionaryAfter the reciting tone, every mode is distinguished by scale degrees called "mediant" and "participant". Source: Internet
The introduction also uses the mediant to tonic relationship, which further distorts the tonic key until, finally, the bassoon plays in its lowest possible register. Source: Internet
The mediant is named from its position between the final and reciting tone. Source: Internet