Definition of "jailer"

Sometimes some of the ejected ministers preached to them privately, and now and then the jailer allowed Mr. H. to go out in the night to preach to them, and administer the Lord's Supper.

1775, Samuel Palmer, The Nonconformist's Memorial‎

But the next morning came, and my coffee was brought by her mother; the next, and the next, by the under jailers; and Angiola continued grievously ill.

1883, Silvio Pellico, chapter 32, in My Ten Years' Imprisonment‎

The jailer was also roused by the earthquake and came to the outer door; he was perhaps a soldier, or at least had something of Roman discipline, giving him presence of mind.

2001, Sir William Mitchell Ramsay, St. Paul: The Traveler and Roman Citizen‎, page 176