Brassica juncea, a mustard plant with edible leaves, seeds, and stem.

Any of several species of the cruciferous genus Erysimum, especially Erysimum cheiranthoides, which was formerly used as an ingredient in Venice treacle, or theriac.

A poultice of mustard seed powder spread inside a protective dressing and applied to the chest or abdomen to stimulate healing.

Turritis glabra (syn. Arabis glabra), a tall, slim, grey-green plant with small creamy flowers at the top of the stem.

Sisymbrium officinale, a brassicaceous plant with edible leaves and seeds.

(idiomatic) To suffice; to be good or effective enough.

(simile) Very keen, enthusiastic, eager.

(technical) Mustard gas.

The hot pungent oil expressed from mustard seeds; used sparingly as a food dressing. / (organic chemistry) The essential oil allyl isothiocyanate, also obtained from mustard seeds.

A vesicant gas, bis (2-chloroethyl) sulfide, (ClC₂H₄)₂S, once used in chemical warfare.