Supermajor and subminor
The interval qualities "supermajor" and "subminor" essentially refer to intervals sharper than major and flatter than minor, respectively.
In just intonation
In some notations and interval naming systems for just intonation, "supermajor" and "subminor" indicate sharping or flatting by a specific predefined comma, such as 64/63 (to reach septimal intervals), 81/80 (to reach acute and grave intervals), or 2048/2025 (to reach 5-limit supermajor and subminor intervals).
In other notations
In, say, 41edo or 53edo (or other similar systems), "upmajor" corresponds to "supermajor", and "downminor" to "subminor".
WIP