Samavadi

The samavadi is the second-most prominent (though not necessarily second-most played) note of a raga in Indian classical music. The primary note of the raga is the vadi; the vadi and samvadi are in most cases a fourth or fifth apart.

A samvadi is a note of special significance.it is like the ministry to the monarch. A performer will typically try to emphasize the samvadi along with the vadi when improvising on a certain raga. The vadi and samvadi can be crucial in defining the raga at hand, and in some cases two ragas with the same arohana and avrohana can be distinguished only by the prominence of their sonant and consonant notes. Eg. Samvadis in shuddha swaras :

...
Wikipedia