A prolonged form of a primary but obsolete {word} ὄμω {omō} for which another prolonged form (ὀμόω omoō om-o'-o) is used in certain tenses. To {swear} that {is} take (or declare on) oath: - swear.
Mat 23:16Woe unto you, ye blind guides, which say, Whosoever shall swearG3660 by the temple, it is nothing; but whosoever shall swearG3660 by the gold of the temple, he is a debtor!
Act 2:30Therefore being a prophet, and knowing that God had swornG3660 with an oath to him, thatG3660 of the fruit of his loins, according to the flesh, he would raise up Christ to sit on his throne;
Heb 4:3For we which have believed do enter into rest, as he said, As I have swornG3660 in my wrath, if they shall enter into my rest: although the works were finished from the foundation of the world.
Heb 7:21(For those priests were made without an oath; but this with an oath by him that said unto him, The Lord swareG3660 and will not repent, Thou art a priest for ever after the order of Melchisedec:)
Jam 5:12But above all things, my brethren, swearG3660 not, neither by heaven, neither by the earth, neither by any other oath: but let your yea be yea; and your nay, nay; lest ye fall into condemnation.
Rev 10:6And swareG3660 by him that liveth for ever and ever, who created heaven, and the things that therein are, and the earth, and the things that therein are, and the sea, and the things which are therein, that there should be time no longer: