thāt (English spelling) that

Japanese: thāt（英語表記）that

...However, unlike musical scales, Melakarta is not a concept derived from actual melodies, but rather a further abstraction of ragas that were once abstracted from actual melodies. The North Indian concept of thāt, although it has only ten in total, is a concept close to the South Indian Melakarta, and it is said that all ragas are based on it. However, in reality, it includes some differences in pitch, so it is not a strict abstraction of raga.

From [Raga]

…(1) Fundamental sequence The theories of the fundamental sequence to which ragas belong differ between North Indian and South Indian music. In North India, ten modes are considered to be the fundamental sequence, called thāt. These are based on the difference in the arrangement of the intervals of semitones, whole tones, and augmented second tones in the octave. …

*Some of the terminology explanations that mention "thāt" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…しかし，メーラカルタは音階のように実際の旋律から得られた概念というより，実際の旋律から一度抽象化されたラーガをさらに抽象化したものである。北インドのタートthātという概念も，全体の数が10個と少ないが，南インドのメーラカルタに近い概念で，すべてのラーガがこれを基礎にしていると説明される。しかし，実際には，音高の点でも多少の差異を含んでいるので，厳密なラーガの抽象化ではない。…