bruñir

To burnish or polish, especially metal, to a shine — a technical verb for metalworking and jewelry, more specific than the general pulir (to polish/smooth). Irregular: like gruñir and tañer, the i of the ending disappears after the ñ (bruñendo, not bruñiendo; bruñó, not bruñió).

• El artesano bruñe la plata hasta que brilla como espejo. — The craftsman burnishes the silver until it shines like a mirror.
• Bruñeron la armadura para la exhibición del museo. — They polished the armor for the museum exhibit.
• Está bruñendo las piezas de cobre en el taller. — He's burnishing the copper pieces in the workshop.

Learners regularize the gerund/preterite as bruñiendo/bruñió by analogy with normal -ir verbs — the ñ absorbs the following i, so it's bruñendo and bruñó, the same pattern as gruñir (gruñendo) and reñir (riñendo).

Often confused with pulir.