🔼The name Ephai in the Bible
The name Ephai occurs only one time in the Bible. Ephai the Netophathite is the (arch-)father of a group of men, who accompany Ishmael, son of Nethaniah, and a good few other men on their visit to Gedaliah, son of Ahikam, who is the appointed vassal over the cities of Judah in service of the king of Babylon. We probably only know about this event because the prophet Jeremiah was staying with Gedaliah at that time (Jeremiah 40:8).
Gedaliah does his best to persuade everyone that serving Babylon is really not a bad deal, and most people seem content with his explanations and take their leave. But Ishmael, son of Nethaniah and a thoroughly unpleasant fellow to boot, returns with ten men and assassinates Gedaliah and proceeds to slaughter pretty much everybody else.
🔼Etymology of the name Ephai
The name Ephai comes from the following root cluster:
The letter י (yod) upon which our name ends, may either create an adjective (such-and-such-like), a possessive form (my such and such), or may be a remnant of יה (Yah) = יהו (Yahu) = יו (Yu), which in turn are abbreviated forms of the Tetragrammaton יהוה, YHWH, or Yahweh.
For a meaning of the name, NOBSE Study Bible Name List goes with עוף I, figures the final י to be an adjective-maker, and reads Bird-Like. Jones' Dictionary of Old Testament Proper Names leans towards the root עיף II, deems the י to be a remnant of יהוה and reads Wearying Of The Lord. BDB Theological Dictionary doesn't interpret this name but does list it under the root עוף II / עיף I ('up), and would probably agree with translations like Dark or Darkling.