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 आपि
आपिāpiObtaining wealth &c.
[आप्-णिच्- इन्]
Obtaining wealth etc.
A friend, acquaintance, ally (बन्धु); denotes that the rest of the word under consideration is to be suppliedत्वम् friendship, alliance; आपित्वे नः प्रपित्वे तूयमा गहि Rv.8.4.3.