Probably strengthened from φθίω phthiō (to pine or waste): properly to shrivel or wither that is to spoil (by any process) or (genitive) to ruin (especially figuratively by moral influences to deprave)

1. to corrupt, to destroy

a. in the opinion of the Jews, the temple was corrupted or "destroyed" when anyone defiled or in the slightest degree damaged anything in it, or if its guardians neglected their duties

b. to lead away a Christian church from that state of knowledge and holiness in which it ought to abide

c. to be destroyed, to perish

d. in an ethical sense, to corrupt, deprave