gamaka

Japanese: gamaka

…However, a scale can be recognized even if the absolute pitch is not stable. In South Indian ragas, decorative melodies called gamakas that constantly oscillate back and forth between two notes, or notes that move up and down in pitch, usually thought of as apposites or apposite sounds, are sometimes included as essential elements of the individual notes that make up the raga. Raga is not the same as a scale, but it is a closely related concept that deserves attention. …

From [Raga]

...The character of a raga is largely determined by the frequency of use of each note, especially in slower pieces. (4) Ornaments: These are collectively called gamaka and refer to distinctive, small movements of notes. These are divided into many types, and which ornaments are primarily used is also a factor in determining the individuality of a raga.

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

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…しかし，絶対音高が安定しなくとも，音階を認めることができる。また南インドのラーガでは，ガマカgamakaという装飾的旋律が常に2音間を往復振動しているような場合や，通常倚音や前打音と考えられるような音高の上下動がある場合も，ラーガを構成する各音の本質的な要素として含めていることもある。ラーガは音階と同じではないが，関連の深い概念なので注目しなければならない。…