The verb disparage means to criticize someone or something with a lack of respect.
Synonyms are belittle, degrade, underrate, or slander.
The word origins in late 14th century. It comes from Anglo-French and Old French desparagier meaning “reduce in rank, degrade, devalue, depreciate”, originally meaning “to marry unequally, marry to one of inferior condition or rank”. It is derived from des- meaning “away” plus parage meaning “rank, lineage”.
The professor made some remarks to disparage the student’s work in the class.
Some people want to disparage this amazing study.
You should not disparage the products that we are always using.