Something noxious is harmful, often in a quiet, poisonous way. People use it most about gases, fumes, smoke, and waste that can make you ill if you breathe them. You can also call an idea or an influence noxious when it poisons the way people think: noxious rumours, a noxious habit in a group. It is a fairly formal, serious adjective; in everyday talk people more often say “poisonous”, “toxic”, or “harmful”. It is stronger than just “unpleasant”: a smell can be nasty without being noxious, though actually news writing sometimes stretches it to mean “really bad”.

有害的、有毒的（多指氣體、廢料；也可形容有害的思想）