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 निर्णिज्
निर्णिज्nirṇij3 U.
3 Ubbayapada (Parasmaipada and Atmanepada)
To wash, clean, purify: अम्बुनिर्णिक्तम् Y.1.191; Ms.5.127.