There is plenty of emphasis on literal meaning already so let's take a slightly different tack and think about what this reveals in a greater depth. If we compare it to its uses in the prophets, the word alone reveals a great deal of both God's character and his values. That, in its turn, gives us a deeper perspective on the word itself and why it is used--why no other word will do.
Many people don't like reading the prophets because they think it's all doom and gloom and God is just being mean and ugly and why can't he just be sweet and kind like we want him to be? Why can't God just live up to our expectations? Why isn't he more who we think he should be? But the answer of course is that he is so much more than we conceive.
"...I am very jealous for Zion; I am burning with jealousy for her." He declares in Zechariah 8:2. This verse uses the primary root, qana, which can more loosely mean zealous and from which the term in Exodus 20:5 (qanna) is taken. The derivative, which is the more specific term,jealousy, is the one God uses in Exodus 34 when he describes himself, and I have to say, I find this highly significant.
God's point of view is not our point of view. We forget that. We judge Him by human standards, but He is not human. He is something completely other and cannot be judged by any standard but the one He sets for Himself. For God, jealousy is a measure of His devotion, his passionate caring; for him it is a fire that consumes His enemies (Deuteronomy 4:24; Zephaniah 1:18) but it also protects and provides (Joel 2:8 and Isaiah 9:7) for those who belong Him.
This quality--something we tend to think of as possessiveness--should probably more accurately be translated "loyalty" in English, for this is the way God uses it. He is absolutely dependably loyal; he keeps his word even when we don't keep ours. His call is irrevocable... This is the loyalty He gives and this is the loyalty He requires for it is the measure of true love and commitment.
We are casual about loyalty. God isn't. We feel slightly guilty at betraying a trust, but it's not the worst thing--it's not like it's murder or something. There is no worse thing in God's lexicon of values: for God everything in the covenant relationship is based on us putting Him and what He requires of us first and foremost in our lives. Everything depends on loyalty and trust.
"In covenant contexts the terms "hate" and "love" (Exodus 20:6) were
conventionally used to indicate rejection of or loyalty to the
covenant Lord." NIV Study Bible Commentary, pg.115
The primary characteristic of this term is the quality of loyalty. God keeps his word--and that is a very scary idea--as well as a comforting one.