Reference for Bikkurim 2:8

כּוֹי, יֶשׁ בּוֹ דְרָכִים שָׁוֶה לַחַיָּה, וְיֶשׁ בּוֹ דְרָכִים שָׁוֶה לַבְּהֵמָה, וְיֶשׁ בּוֹ דְרָכִים שָׁוֶה לַבְּהֵמָה וְלַחַיָּה, וְיֶשׁ בּוֹ דְרָכִים שֶׁאֵינוֹ שָׁוֶה לֹא לַבְּהֵמָה וְלֹא לַחַיָּה:

A <i>Koi</i> [animal of ambiguous status, exhibiting characteristics of wild and domesticated animals] is similar to a wild animal in some ways, and is similar to a domestic animal in other ways, and is similar to both in some ways, and is like neither in other ways.

Jastrow