noxious

Everyday

1. Harmful or poisonous, especially gases, fumes and chemicals. tree →
2. Very unpleasant, as in "a noxious smell". tree →
3. (of plants) Harmful weeds that are a pest to farms, as in "noxious weeds" (Australia, US, Canada). tree →

In the lessons

Used in science and safety (noxious gases from cars, factories or fires can make people ill; never mix cleaning products because they can give off noxious fumes) and in stories about smells. In Australia and North America "noxious weeds" are plants landowners must control by law.

Examples

• The factory let out noxious fumes. tree →
• Never mix bleach with other cleaners; it makes noxious gases. tree →
• A noxious smell came from the drain. tree →
• Some plants are listed as noxious weeds. tree →
• Car exhaust contains noxious gases. tree →
• The witch stirred a noxious green potion. tree →
• The firefighters wore masks against the noxious smoke. tree →
• By the influence of his warm and gentle rays he disperses the noxious vapours of the night, assists the grain to ripen and the flowers to bloom. tree →

Note

Formal; everyday words: "harmful", "poisonous", "toxic". Pronounced "NOK-shus". Safety: if you smell strong fumes, get to fresh air and tell an adult.