ὑποζύγιονhypozýgion

under the yoke; as as a noun, τὸ ζ., a beast of burden; colloq., an ass, and so always in LXX and NT: Matthew 21:5 (LXX), 2 Peter 2:16.

Greek (New Testament) · G5268

Same root

ὑπόhypó · G5259under, i.e. (with the genitive case) of place (beneath), or with verbs (the agency or means, through); (with the accusative case) of place (whither (underneath) or where (below) or time (when (at))
ζυγόςzygós · G2218a coupling, i.e. (figuratively) servitude (a law or obligation); also (literally) the beam of the balance (as connecting the scales)

Where it appears

Appears 2 times in the Bible.

Matthew 21:5 “Tell the people of Jerusalem, ‘Look, your King is coming to you. He is humble, riding on a donkey— riding on a donkey’s colt.’”
2 Peter 2:16 But Balaam was stopped from his mad course when his donkey rebuked him with a human voice.

Source: G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922), public domain.