Disbelieve
From BiblePortal Wikipedia
Vine's Expository Dictionary of NT Words [1]
1: Ἀπιστέω (Strong'S #569 — Verb — apisteo — ap-is-teh'-o )
"to be unbelieving" (a, negative, pistis, "faith;" cp. apistos, "unbelieving"), is translated "believed not," etc., in the AV (except in 1—Peter 2:7 , "be disobedient"); "disbelieve" (or "disbelieved") in the RV, in Mark 16:11,16; Luke 24:11,41; Acts 28:24; "disbelieve" is the best rendering, implying that the unbeliever has had a full opportunity of believing and has rejected it; some mss. have apeitheo, "to be disobedient," in 1—Peter 2:7; Romans 3:3 , RV, "were without faith;" 2—Timothy 2:13 , RV, "are faithless. Cp. Disobedient, C. See Believe
Webster's Dictionary [2]
(v. t.) Not to believe; to refuse belief or credence to; to hold not to be true or actual.