snib

To the same root as snub. For the sense reprimant, compare cognate Old Norse sneypa (“to rebuff, infringe, etc”). The etymology appears visible in Nordic cognates, to an original sense of “pinching off” (→ “to repress, infringe”), really “snipping off” (Old Norse sneypa, Norwegian Nynorsk snøypa, Swedish snöpa, snoppa, snipa, snippa (“to pinch off, to squeeze off, to castrate”)), with nouns denoting “pinched end → point” (cf. Swedish snip (“snout, spout”), snibb (“lobe”)).

The latch sense could stem from older latches which were lobe-shaped, then analog to Swedish snibb (“lobe”). Another idea could be that the 'latch action' derives from the action of “pinching off” becoming “closing off”. A third idea could be that it derives from reprimanding through “locking” a door. The term may also have been affected by words like snap via the “snapping” action of a latch.