The phrase "lengthy hiatus" means a long break or pause in an activity, usually implying a significant amount of time has passed since it last occurred. Full definition
That item, in May 2011, was one of the last posts Mr. Szabo made before he went on a lengthy hiatus to work, he said later, on a new concept he called temporal programming. (nytimes.com)
«The Los Alamos Plutonium Facility is a unique and essential national security capability,» McMillan, the lab's director, said last September during a visit by then - Defense Secretary Ashton Carter, who watched as technicians — attempting to restart their work after the lengthy hiatus — used pressing machines and other equipment to fabricate a mock pit, rather than a usable one. (sciencemag.org)
One of the most poignant moments comes when former choir member Fred Knittle returns after a lengthy hiatus caused by heart problems. (parentpreviews.com)