To cover completely; to envelop or hide something entirely. Can be used literally or figuratively for something spreading over an area.
雪が街を覆い尽くし、通りは白一色になった。
Snow covered the town completely, and the streets turned entirely white.
ツタが古い壁を覆い尽くして、建物の輪郭が判らなくなった。
Ivy had wrapped around the old wall so much that the building's outline became indistinguishable.
暗闇が希望を覆い尽くしているように感じたが、やがて光が差した。
It felt as if darkness was enveloping hope completely, but eventually light broke through.