demeritar

Used mainly in Mexican and other Latin American Spanish to mean to detract from someone's merit or to disparage/diminish their worth (esto no demerita su trabajo). It's less common in Spain, where restar méritos or desmerecer are more typical.

• Eso no demerita todo el esfuerzo que hizo. — That doesn't diminish all the effort he made.
• No quiero demeritar tu trabajo, pero hay errores. — I don't want to disparage your work, but there are mistakes.
• Su actitud demeritó la buena impresión inicial. — His attitude undermined the good first impression.

Assuming demeritar is standard everywhere — it's a regionalism, chiefly Mexican; desmerecer is the form more broadly recognized across the Spanish-speaking world.

Often confused with desmerecer.