to act as a shepherd toward: to feed, guard, lead and govern those in one's charge
Shepherding in the Bible is not one task but a whole job. The person who does it walks the animals to grass and water, keeps predators off, carries the ones that cannot keep up, brings them back in at night, and answers for any that are missing. This verb names that entire round of work, which is why it can stretch from a farmhand out with sheep to Christ over the nations without changing at the core.
The stretch is possible because kings in the ancient world were routinely called shepherds of their people. When God tells David that he will shepherd Israel, the picture is not a soft one: a shepherd has real authority and is expected to use it. That is the bridge between the gentlest use of this word, the Lamb leading the rescued to springs of water, and the hardest, a ruler breaking the nations like clay pots. Both are a shepherd doing what his position gives him the power to do.
The New Testament then hands the word to church leaders, and the choice is deliberate. Elders are not told to manage, preside, or lecture. They are told to shepherd, which brings the whole round of duties with it, along with the assumption that the flock belongs to someone else. Peter's charge, Paul's warning at Miletus, and Jesus' command to Peter all use it, and Jude turns it inside out to accuse men who do a shepherd's work on nobody but themselves.
Nearby Greek words each cover only a slice of what this one covers:
Nuances
Whether the verb in Revelation 2:27, 12:5 and 19:15 retains its shepherding sense of ruling and guiding a flock, or functions as a verb of destruction taken over from the Septuagint rendering of Psalm 2:9 (where the Hebrew consonants of תְּרֹעֵם, from רעע "to break", were vocalized instead as a form of רעה "to shepherd").
- contestedThe shepherd image remains active and is exploited deliberately: the Messiah and his people rule the nations as a shepherd rules, and the iron rod is the shepherd's club turned to judgment, deliberately paired with the Lamb's pastoral care in Revelation 7:17.; G. K. Beale, The Book of Revelation, NIGTC (Grand Rapids: Eerdmans, 1999)
- contestedThe verb has lost its pastoral force in these contexts and functions as a verb of violent subjugation, its sense governed by the destruction imagery of the Psalm 2 context and by the smashed pottery of the following clause.; David E. Aune, Revelation 1-5, WBC 52A (Dallas: Word, 1997)