a fault in sth or in the way it has been made which means that it is not perfect 缺点；缺陷；毛病
a speech defect
言语缺陷
a defect in the glass
玻璃杯的缺陷
[I] ~ (from sth) (to sth)to leave a political party, country, etc. to join another that is considered to be an enemy 背叛；叛变；投敌