fog

a thick cloud of water droplets in the air that reduces visibility and makes everything look white or grey

niebla, neblina

• foggy morning

Collocations dense fog · heavy fog

• The fog was so thick that I couldn't see the road.

  La niebla era tan densa que no podía ver la carretera.

software or a system that controls how other software works on a computer

sistema operativo, sistema de control

• operating system

Collocations Windows operating system · Linux operating system

• The computer's operating system needs updating.

  El sistema operativo del ordenador necesita actualizarse.