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.
tvadanyaḥ saṁśayasyāsya chettā na hyupapadyate. — This my doubt, O Krishna, please dispel completely without leaving any residue; for there is none else than Thyself who can destroy this doubt. 6·39
छेत्ताchettānominative singular of the masculine noun chettṛ (the destroyer).