Where does “คณิต” come from?

คณิต (Thai) comes from Sanskrit गणित, from Sanskrit शास्त्र, from Proto-Indo-Aryan śāstra.

Ancestry of “คณิต”, step by step

Step	Language	Word	Meaning
1	Sanskrit	गणित	mathematics
2	Sanskrit	शास्त्र	shastra, scripture; science, knowledge
3	Proto-Indo-Aryan	śāstra	—

คณิต — Etymology, Origin & Word History | Etymology Explorer