Meaning of “burn (sth) down” - Learner’s Dictionary

burn (sth) down

phrasal verb with burn uk us /bɜːn/ verb (past tense and past participle burnt, burned)

B2 to destroy something, especially a building, by fire, or to be destroyed by fire:

Their house burnt down while they were at work.

(Definition of “burn (sth) down” from the Cambridge Learner’s Dictionary © Cambridge University Press)