Definition of Tom Thumb in English:

Tom Thumb

noun

  • 1[usually as modifier] A dwarf variety of a cultivated flower or vegetable.

    ‘Tom Thumb lettuce’
  • 2A small wild flower, especially bird's-foot trefoil.

Origin

Late 19th century: from the name of the hero of a children's story, a ploughman's son who was only as tall as his father's thumb.