Like other jellies, the ochre jelly has a passive to watch out for that can corrode iron or copper objects. However, they can also chase and engulf you - this covers you in acidic slime, but does not corrode objects.
Ochre jellies are still quite slow and can be easily outrun, allowing you to pick them off at a distance with corrode-proofed or disposable projectiles - you can also simply run away if you aren't prepared to handle them. Their passive acid attack does 3d6 damage as opposed to the (XL + 1)d6 of spotted and blue jellies, but being engulfed may force you to attack and trigger this passive multiple times. A wand of digging or spell of dig will immediately free you and reduce their HP to 1.
For players keeping mind flayer pets or using the polyform, each tentacle attack will trigger the passive; acid resistance via yellow dragon scales/scale mail (or a spare alchemy smock for polymorphed players) will easily counteract this.
The following information pertains to an upcoming version (3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.After this commit, monsters now gain acid resistance from a worn alchemy smock.
The ochre jelly was introduced in NetHack 3.0.0.
In SLASH'EM, the engulfing attack can corrode objects in open inventory, including your alignment key.