Metal grilles are a type of architectural feature that is often used to provide ventilation, security, or decoration. They are typically made from metal and have a lattice-like pattern of bars or rods. The term 'metal grille' can also refer to a type of metal mesh used in air conditioning systems. The crossword solution for the term 'metal grille' is 'GRATE, ' which is a noun meaning a framework of metal bars or wires used as a partition or as a covering for an open space.