“φόβῳ” (BDAG) = “the product of an intimidating/alarming force” 

1. The product could be “fear, alarm, fright”

   1. Could be fear, anxiety, apprehension, fear of death, fear of someone, enslaved to fear.

2. The product could be “reverence, respect”

   1. Toward God (THIS CONTEXT IN EPHESIANS 5:21)

      1. Phil. 2:12 — “continue to work out your salvation with fear and trembling”

      2. Rom. 3:18 — “There is no fear of God before their eyes.” (quote of Ps. 36:1)

      3. 2 Cor. 7:1 — “Therefore, since we have these promises, dear friends, let us purify ourselves from everything that contaminates body and spirit, perfecting holiness out of reverence for God.” (Interestingly, P46 substitutes “agape” for “phobo” here. This may signal that the early church saw a semantic overlap between the words “reverence” and “love”, at least theologically)

      4. Acts 9:31 — “Then the church throughout Judea, Galilee and Samaria enjoyed a time of peace and was strengthened. Living in the fear of the Lord and encouraged by the Holy Spirit, it increased in numbers.”

      5. 2 Cor. 5:11 — “Since, then, we know what it is to fear the Lord, we try to persuade others.”

      6. 1 Peter 1:17 — “live out your time as foreigners here in reverent fear” (assuming that God is the object of this fear, which is debated by interpreters).

   2. Toward humans

      1. Rom. 13:7ab — “Give to everyone what you owe them: If you owe taxes, pay taxes; if revenue, then revenue; if respect, then respect; if honor, then honor.”

      2. 1 Peter 2:18 — “Servants, be subject to your masters with all respect” (ESV)

      3. Eph. 6:5-8 — “Slaves, obey your earthly masters with respect and fear (fear and trembling, “μετὰ φόβου καὶ τρόμου”, same phrase as Phil. 2:12), and with sincerity of heart, just as you would obey Christ. Obey them not only to win their favor when their eye is on you, but as slaves of Christ, doing the will of God from your heart. Serve wholeheartedly, as if you were serving the Lord, not people, because you know that the Lord will reward each one for whatever good they do, whether they are slaves or free.”

      4. 1 Peter 3:1-2ff — “Wives, in the same way (as submission to authorities, following the example of Christ, see 2:1-25) submit to your own husbands so that, if any of them do not believe the word, they may be won over without words by the behavior of their wives, when they see the purity and reverence of your lives…”

      5. 1 Peter 3:15b-16 — “…Always be prepared to give an answer to everyone who asks you to give a reason for the hope that your have. But do this with gentleness and respect.”