mustard gas noun

The vapour from a poisonous blistering liquid, (CH₂ClCH₂)₂S, obtained from ethylene and sulphur chloride (also called dichlorodiethyl sulphide)

mustard oil noun

A volatile oil obtained from black mustard seeds

mustard plaster noun

A counter-irritant skin application made from black and white mustard flour, deprived of their fixed oil

mustard tree noun

A name given to a shrub Salvadora persica (family Salvadoraceae, prob related to Oleaceae) on the theory that it is the plant referred to in the New Testament, which others think is only black mustard which has grown tall, as it does in the Middle East

black mustard

An annual herb (Brassica nigra), whose strongly-flavoured seeds are used in cookery

cut the mustard (informal)

1. Reach a required standard, make the grade
2. Make a favourable impression on

French mustard

The condiment prepared for the table by adding salt, sugar, vinegar, etc

garlic mustard see under garlic

hedge-mustard see under hedge

keen as mustard (informal)

Intensely enthusiastic

Sarepta mustard

An annual herb (Brassica juncea), whose seeds and oil are used in cookery (also brown mustard)

white mustard

An annual herb (Brassica alba) of the Mediterranean region, whose seeds are used in cookery

wild mustard

Charlock, a common cornfield weed with yellowy flowers