Scathing means fiercely and woundingly critical. Not a complaint — an attack that leaves marks.
It attaches to criticism, attacks, reviews and remarks, and a scathing review is one an author remembers for life. The word implies both severity and skill, since a scathing attack is well aimed as well as harsh. It comes from an old verb scathe meaning to harm, which survives elsewhere only in unscathed, meaning unharmed. That pairing is worth noticing, since unscathed is far commoner than scathe itself.
1adjectivescathingSeverely and woundingly critical.
“The report was scathing about the management.”