In the book of Exodus 20:5 we can find the sentence “For I, the Lord your God, am a jealous God” (NKJV), “ἐγὼ γάρ εἰμι Κύριος ὁ Θεός σου, Θεὸς ζηλωτής“.
The noun “ζηλωτής” (pronunciation: zelotes, definition: zealous, dedicated admirer or follower, jealous) is a masculine noun in Greek language that derives from the verb “ζηλόω/ζηλῶ [1] ( pronunciation: zeloō, definition: to be zealous or jealous, to have warmth of feeling for or against). [2]
[1]https://el.m.wiktionary.org/wiki/%CE%B6%CE%B7%CE%BB%CF%89%CF%84%CE%AE%CF%82
[2] Hebrew-Greek Key word Study Bible, KJV, AMG Publishers