Godan verb with 'su' ending, Transitive verb
to burn completely; to consume (by fire); to burn to nothing; to burn to the ground; to reduce to ashes
その火は東風にあおられて市の中心部を焼き尽くした。The fire, driven by an east wind, destroyed the center of the city.
Also written 焼きつくす【やきつくす】、焼き尽す【やきつくす】