Mediant Scale Degree
From “The Mediant: The 3rd Third Scale Degree¨ in Music Theory for Electronic Music Producers
So, for example, for the C Major scale, the third scale degree would be E:

music music_theory major_scale scale_degree pitch pitches root_key root_pitch
bibliography
- “The Mediant: The 3rd Third Scale Degree.” In Music Theory for Electronic Music Producers: The Producer’s Guide to Harmony, Chord Progressions, and Song Structure in the MIDI Grid., 1st ed., 61. Minneapolis, MN: Slam Academy, 2018.