1: ὅρκος
(Strong's #3727 — Noun Masculine — horkos — hor'-kos, her'-kos )

is primarily equivalent to herkos, "a fence, an enclosure, that which restrains a person;" hence, "an oath." The Lord's command in Matthew 5:33 was a condemnation of the minute and arbitrary restrictions imposed by the scribes and Pharisees in the matter of adjurations, by which God's Name was profaned. The injunction is repeated in James 5:12 . The language of the Apostle Paul, e.g., in Galatians 1:20; 1—Thessalonians 5:27 was not inconsistent with Christ's prohibition, read in the light of its context. Contrast the "oaths" mentioned in Matthew 14:7,9; 26:72; Mark 6:26 .

Hebrews 6:16 Luke 1:73Acts 2:30
2: ὁρκωμοσία
(Strong's #3728 — Noun Feminine — horkomosia — hor-ko-mos-ee'-ah )

denotes "an affirmation on oath" (from No. 1 and omnumi, "to swear"). This is used in Hebrews 7:20,21 (twice),28 of the establishment of the Priesthood of Christ, the Son of God, appointed a Priest after the order of Melchizedek, and "perfected for evermore." In the Sept., Ezekiel 17:18,19 .

Acts 23:21CURSE.