to let something happen or let something be, by not stepping in to stop it
At its heart this word describes a decision not to interfere. Someone has the power to step in and stop what is happening, and does not use it. That single idea covers everything the word does in the New Testament: a homeowner who would not have let a thief break in, soldiers who cut a lifeboat loose and let it drop away, and God who left earlier generations to walk their own roads.
Six of its eleven appearances in the New Testament are negative, and that shapes how it lands in English. When Luke writes that the Spirit of Jesus "did not allow" Paul and his companions to enter Bithynia, or that Paul's friends "would not let" him face the crowd at Ephesus, the force is close to a refusal. But the Greek still says only that permission was withheld, not that anyone was physically held back.
Greek had sharper words close by. There was a verb for permission formally granted by someone who has the standing to grant it (ἐπιτρέπω), and a positive verb for hindering or blocking someone (κωλύω). This word sits between them as the plain verb for letting something run its course. Its widest neighbor, the verb for releasing, abandoning, and forgiving (ἀφίημι), reaches much further than any of them.
Once the word slides away from permitting toward simply letting go. When the sailors in Acts 27 cut away the anchors, they "left them in the sea," with no thought of permission at all. And in one famously difficult line, Luke 22:51, Jesus answers the sword stroke in the garden with a short phrase that translators still cannot agree on: versions run from "No more of this!" to "Permit even this."
Nuances
In Luke 22:51 the imperative ἐᾶτε ἕως τούτου stands without a stated object, so both the addressee and the thing permitted are left open, and interpreters divide over how to construe it.
- majorityJesus addresses his own followers and tells them to break off the armed resistance; the phrase works as an abrupt command and is best rendered "Stop! No more of this!"; Frederick W. Danker, ed., A Greek-English Lexicon of the New Testament and Other Early Christian Literature, 3rd ed. (BDAG; Chicago, 2000), s.v. ἐάω, which records "stop, no more of this" as the first option; Joseph A. Fitzmyer, The Gospel According to Luke X-XXIV (Anchor Bible 28A; Doubleday, 1985), on 22:51
- minorityJesus addresses those arresting him and asks them to let him go this far, that is, to allow him to touch and heal the servant's ear before he is led away.; Frederick W. Danker, ed., A Greek-English Lexicon of the New Testament and Other Early Christian Literature, 3rd ed. (BDAG; Chicago, 2000), s.v. ἐάω, which records "permit me to go this far," that is, to heal, as a live alternative