ὑπεναντίοςhypenantíos

under (covertly) contrary to, i.e. opposed or (as noun) an opponent

Greek (New Testament) · G5227

Meanings

set over against, opposite. Metaph., opposed to, contrary to: with dative of person, Colossians 2:14; absolutely, as as a noun, ὁ ὑ., Hebrews 10:27 (cf. Isaiah 26:11).

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))
ἐναντίοςenantíos · G1727opposite; figuratively, antagonistic

Where it appears

Appears 2 times in the Bible.

Colossians 2:14 He canceled the record of the charges against us and took it away by nailing it to the cross.
Hebrews 10:27 There is only the terrible expectation of God’s judgment and the raging fire that will consume his enemies.

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