1: οὐδέποτε
(Strong's #3763 — Adverb — oudepote — oo-dep'-ot-eh )

from oude, "not even," and pote, "at any time," is used in definite negative statements, e.g., Matthew 7:23; 1—Corinthians 13:8; Hebrews 10:1,11 , or questions, e.g., Matthew 21:16,42; in Luke 15:29 (1st part), RV, "never" (AV, "neither ... at any time"); AV and RV, "never" (2nd part).

2: μηδέποτε
(Strong's #3368 — Adverb — medepote — may-dep'-ot-eh )

virtually the same as No. 1, the negative me, however, conveying a less strong declarative negation, 2—Timothy 3:7 .

3: οὐδέπω
(Strong's #3764 — Adverb — oudepo — oo-dep'-o )

"not yet," is translated "never (man) yet" in John 19:41 ("man" representing the idiomatically used negative pronoun oudeis, "no one"); some mss. have it in Luke 23:53 , instead of oupo, "not yet."

Mark 14:21John 7:15John 4:148:51,5210:2811:2613:8Mark 3:29 2—Peter 1:10John 6:35 Luke 19:30