अष्ठीवत्

From Proto-Indo-Aryan *HaṣṭʰiHwánts, from Proto-Indo-Iranian *HastčiHwánts. Cognate with Old Armenian ճիւ (čiw).

Lubotsky suggests that this word was certainly influenced by अस्थि (ásthi, “bone”), in part due to the rare cluster -ṣṭh-, possibly reflecting an earlier Rigvedic astcīvát.

• (Vedic) IPA^(key): /ɐʂ.ʈʰiː.ʋɐ́t/
• (Classical Sanskrit) IPA^(key): /ɐʂ.ʈʰiː.ʋɐt̪/

अष्ठीवत् • (aṣṭhīvát) stem, m (Vedic astcīvát)

1. shank, shin

As shown by Lubotsky, the correct meaning is “shank, shin”, not “the knees”, as is usually thought.

• Early Assamese: আণ্ঠু (aṇṭhu)
  • Assamese: আঁঠু (ãthu), আণ্ঠু (anthu)
• Bengali: হাঁটু (hãṭu)
• Sylheti: ꠀꠑꠥ (aṭú)

• Lubotsky, Alexander (2002) “The Indo-Iranian Word for ‘shank, shin’”, in Journal of the American Oriental Society‎^[1], volume 122, number 2, pages 318–324