V. S. Apte, The Practical Sanskrit–English Dictionary. Look up any word of the Gita in Devanagari, IAST or Harvard-Kyoto, or browse the headwords letter by letter.
Entry तर्किन्
तर्किन्tarkina.Guessing.
[तर्क्-णिनि]
Guessing.
Reasoning, versed in speculation; Ms.12.111. -Masculine A logician, reasoner.