loaded to excess or impeded by a heavy load; "a summer resort...encumbered with great clapboard-and-stucco hotels"- A.J.Liebling; "a hiker encumbered with a heavy backpack"; "an encumbered estate"
being of crucial importance; "a pivotal event"; "Its pivotal location has also exposed it to periodic invasions"- Henry Kissinger; "the polar events of this study"; "a polar principal"