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 बिल्मम्
बिल्मम्bilmamVed.
Vedic
A (broken) helmet.
A slip, hit, chip; सं सानु मार्ज्मि दिधिषामि बिल्मैः Rv.2.35.12.