1: ἀθλέω
(Strong's #118 — Verb — athleo — ath-leh'-o )

"to engage in a contest" (cp. Eng., "athlete"), "to contend in public games," is used in 2—Timothy 2:5 , RV, "contend in the games," for the AV, "strive for the masteries." See STRIVE.

1—Corinthians 9:25
2: διακρίνω
(Strong's #1252 — Verb — diakrino — dee-ak-ree'-no )

lit., "to separate throughout or wholly" (dia, "asunder," krino, "to judge," from a root kri---, meaning "separation"), then, to distinguish, decide, signifies, in the Middle Voice, "to separate oneself from, or to contend with," as did the circumcisionists with Peter, Acts 11:2; as did Michael with Satan, Jude 1:9 . See RV marg. of Jude 1:22 , where the thought may be that of differing in opinion. See DIFFER , DISCERN , DOUBT , JUDGE , PARTIAL , STAGGER , WAVER.

3: ἐπαγωνίζομαι
(Strong's #1864 — Verb — epagonizomai — ep-ag-o-nid'-zom-ahee )

signifies "to contend about a thing, as a combatant" (epi, "upon or about," intensive, agon, "a contest"), "to contend earnestly," Jude 1:3 . The word "earnestly" is added to convey the intensive force of the preposition.