to sit down: to lower oneself onto a seat or mount, and so to take one's place
TranslatabilityApproximateCertaintySettled
This is by far the most common use of the word: a person sits down. In the Gospels it is the natural thing a teacher does before he speaks, so it often marks the moment a lesson begins, as when Jesus sits down on the mountain or in the boat and the crowd settles to listen.
Sitting also carries weight beyond simple rest. To sit is to take up a position, whether on a borrowed colt before riding into Jerusalem, or on a chair of authority. That second shade leads naturally into sitting as a posture of rule and judgment, gathered under the next sense.
Because the action is so ordinary, the word rarely needs more than its plain English equivalent here. The interest lies in why a writer mentions the sitting at all, which is usually to signal that something important is about to be said or done.
Nuances
1ato sit down in the ordinary way, often in order to teach, watch, or settle in
to seat someone, to set or install a person in a position
TranslatabilityPartialCertaintySettled
Here the word turns active toward another person or toward oneself: not just sitting, but causing someone to sit. The clearest cases are God seating the risen Christ at his right hand, and the promise that a descendant of David would be set on his throne. Installing someone in a seat of honor and granting them the authority that goes with it are the same act.
The word can also be used dismissively, as when Paul asks the Corinthians why they install the least respected members of the church as judges of trivial disputes. And it can be turned on oneself: the lawless figure of the end seats himself in the temple, claiming a throne that is not his.
English usually needs more than one word to carry this, since the choice between seat, set, install, and appoint depends on whether honor, office, or sheer presumption is in view.
Act 2:301Co 6:4Eph 1:202Th 2:4*
3
to settle, to stay or remain in a place
TranslatabilityApproximateCertaintySettled
From the idea of sitting down comes the sense of settling in and staying put. When Paul stayed in Corinth for a year and a half teaching, the word does not mean he literally sat the whole time, but that he put down roots and remained. The risen Jesus tells the disciples to stay in the city until they are clothed with power, again the sense of remaining rather than sitting.
The same picture lies behind the tongues of fire at Pentecost, which settled and rested on each of the disciples. The motion stops and the thing comes to rest in place.
This is a recognized but minor use, and English carries it well with stay, settle, or remain rather than sit.
Names the ACT of sitting down, the move into a seated posture, often the deliberate gesture by which a teacher begins to teach: Jesus sits down on the mountain, in the synagogue, in the boat, in the temple, and then speaks.Mat 5:1Luk 4:20Luk 5:3Jhn 8:2
Marks the decisive, completed sitting-down of enthronement: after his work Christ sat down at God's right hand, a single act of taking the throne rather than the long state that follows it.Mrk 16:19Heb 1:3Heb 8:1Heb 10:12Heb 12:2
Can be causative, to SEAT someone or set them in place rather than to sit oneself: God seated Christ at his right hand, and a church is told whom to set up to judge.Eph 1:201Co 6:4
Both
Both put a person on a throne, and Matthew 19:28 uses them side by side so the difference shows plainly: the Son of Man takes his seat (the act, G2523) and the disciples will then be seated (the resulting state, G2521), each on thrones to judge.Mat 19:28
Both can place the exalted Christ at the right hand of God, one viewing it as the act of sitting down there, the other as remaining seated there, so the same enthronement is told either way.Heb 1:3Heb 1:13
Names the ongoing STATE of being seated: someone who remains in place, dwelling or settled rather than moving to sit. The one enthroned in heaven is continuously the One seated on the throne, his reign pictured as an unbroken posture.Rev 4:2Rev 5:1Rev 19:11
Describes people fixed in a condition or location, with no act of sitting down in view: those who sit in darkness, the crowd sitting in the marketplace, the woman sitting in the courtyard.Mat 4:16Mat 11:16Mat 26:69
Used for a person stationed and waiting in one spot, the blind beggar sitting by the road, with the emphasis on where he stays, not on his having taken the seat.Mrk 10:46Act 3:10
Can put someone else in a seat: God seats the risen Christ at his own right hand, God swore to set one of David's descendants on his throne, and Paul asks why the church appoints the people it thinks least of to settle its disputes.Eph 1:20Act 2:301Co 6:4
Taking the seat is taking up authority. Sitting at God's right hand, sitting on a throne of glory, or taking the official bench to hear a case are all acts of assuming a position, not just a change of posture.Heb 1:3Mat 25:31Jhn 19:13Mat 23:2
Can mean to settle in and remain somewhere for a stretch of time, which is why it is sometimes rendered "stay" rather than "sit".Luk 24:49Act 18:11
The seat can be an animal's back, so the word covers getting on and riding.Jhn 12:14Mrk 11:2Mrk 11:7
The one taking the place need not even be a person: what looked like flames of fire came to rest on each of them.Act 2:3
Both
Both describe an ordinary person seated in an ordinary place, and English Bibles render both simply "sat" or "sat down".Jhn 11:20Act 16:13
Both describe the seated posture a teacher takes to teach, which was the normal position for giving instruction.Mat 26:55Luk 2:46Jhn 8:2Luk 5:3
Pictures a person already settled in place, someone found or noticed sitting, rather than the moment of taking a seat.Luk 2:46Jhn 20:12Act 6:15
Always describes the sitter's own posture. It never puts another person into a seat, so no one is ever installed or given a place by this word.Jhn 4:6Act 20:9
Carries the sense of staying put while everything else moves: Mary keeps sitting at home while Martha goes out, and a tired traveler simply stops at a well.Jhn 11:20Jhn 4:6Mat 26:55
kathizō in the other biblical languages
יָשַׁבHebrew“to dwell”the broad Hebrew verb that covers sitting, dwelling, and remaining, often standing behind the Greek when the Old Testament is in view
What scholars say about kathizō
Standard lexica treat καθίζω as the causative-then-intransitive counterpart to κάθημαι. BDAG divides it into a transitive use (cause to sit down, seat, appoint, install) and an intransitive use (sit down, take one's seat), with a further intransitive extension to settle or stay in a place. The intransitive sitting frequently functions as the formal posture of a teacher and, in enthronement and tribunal contexts, as the assumption of authority to reign or to judge, a usage prominent in Hebrews' citation of Psalm 110:1 and in Matthean judgment scenes. The settle/remain sense (Acts 18:11;Luke 24:49) is well attested in Hellenistic Greek and corresponds to a common range of Hebrew yashab, the verb most often rendered by this word group in the Septuagint.
Sources
BDAG, s.v. καθίζωlexicon
LSJ, s.v. καθίζωlexicon
Louw-Nida, Greek-English Lexicon of the New Testament Based on Semantic Domains, domains 17.13, 37.103, 85.65lexicon