Strong's G3660 — ὀμνύω (verb)
omnuo (om-noo'-o) v.
1. to swear, i.e. take (or declare on) oath
[a prolonged form of a primary, but obsolete omo, for which another prolonged form omoo   om-o'-o is used in certain tenses]
KJV: swear 
Occurrences: 26