Definition of mustard seed in English:

mustard seed

Pronunciation /ˈmʌstəd siːd/

noun

  • 1The seed of a mustard plant.

  • 2Used allusively with reference to the mustard seed described in the New Testament (Matthew 13:31); (hence) a small thing capable of vast development. Especially in "grain of mustard seed".

    The mustard seed (κόκκος σινάπεως) of the New Testament, spoken of as producing a tree, is probably the seed of the black mustard (Brassica nigra) which in Israel grows to a great height. However, some commentators have identified it with the toothbrush tree, Salvadora persica.

  • 3US With singular agreement: very fine shot used for shooting birds while causing little injury to the plumage.

Origin

Late Middle English. From mustard + seed.