A — 1: ἀνήμερος
(Strong's #434 — Adjective — anemeros — an-ay'-mer-os )

signifies "not tame, savage" (from a, negative, and hemeros, "gentle"), 2—Timothy 3:3 . Epictetus describes those who forget God as their Creator, as resembling lions, "wild, savage and fierce" (anemeroi) (Moulton and Milligan, Greek Test. Vocab.).

A — 2: χαλεπός
(Strong's #5467 — Adjective — chalepos — khal-ep-os' )

"hard," (a) "hard to do or deal with, difficult, fierce," is said of the Gadarene demoniacs, Matthew 8:28; (b) "hard to bear, painful, grievous," said of the last times, 2—Timothy 3:1 , RV, "grievous," for AV, "perilous." See GRIEVOUS.

James 3:4 Luke 23:5
B — 1: θυμός
(Strong's #2372 — Noun Masculine — thumos — thoo-mos' )

"hot anger, wrath," is rendered "fierceness" in Revelation 16:19; 19:15 , of the wrath of God. See ANGER (A, Notes), INDIGNATION , WRATH.

B — 2: ζῆλος
(Strong's #2205 — Noun — zelos — dzay'-los )

"zeal, jealousy," is rendered "fierceness" in Hebrews 10:27 , RV (of fire).