at fault (in adjectival contexts)

guilty, responsible, to blame. / Of hunting dogs: unable to find the scent.

Full of faults or sins.

plural of faulting

A divorce requested simply because of the breakdown of the marriage, without the requirement to prove a fault on the part of one of the spouses.

(sports) In certain sports, as in tennis or long jump, a fault in which the athlete's foot is in the wrong place at the wrong time.

(tennis) The missing of both the first serve and second serve, resulting in a point for the receiver.

(geology) A geological fault separating two tectonic plates which are sliding horizontally in directions parallel with the fault line.

(intransitive, idiomatic) To criticize excessively / (transitive, idiomatic) (followed by with) To criticize (something) excessively

Alternative spelling of fault line