Jawbreaking

Lord Cockburn, whose forte was not the civil law, affected to listen attentively and take ample notes, when, at last, on Mr Brodie citing some German civilian with a jawbreaking name, his lordship interrupting him asked, […]

Source: wiktionary

If he had, he would probably write and talk in a jawbreaking technical language that we ordinary mortals could not more understand readily than we can work a cross-word puzzle without resorting to the dictionary.

Source: wiktionary