noun

• (countable, uncountable) Maranta arundinacea from the Marantaceae family, a large perennial herb native to the Caribbean area with green leaves about 15 centimeters long.
  "The East India arrowroot was considered the best; and the French West India arrowroot not so good. The East India arrowroot had the finest grains; the second finest were those from the potato; and third the tous les mois or French West India arrowroot; […]"
• (countable, uncountable) Usually preceded by an attributive word: some other plant whose rhizomes are used to prepare a substance similar to arrowroot (sense 3), such as Zamia integrifolia (Florida arrowroot) or Pueraria montana var. lobata (Japanese arrowroot or kudzu).
  "Arrowroot (pia) is a member of the Tacca family. […] The ancient Hawaiians used the arrowroot (pia) as a food and as a medicine."
• (uncountable) A starchy substance obtained from the rhizomes of an arrowroot plant used as a thickener.
  "Dr. Ifill could state, with certainty, that all the arrow-root imported into this country from Barbadoes, was made from the maranta; […] The difference in the quality of the arrow-roots imported into this country, depended on the care which had been employed in the preparation. The greater number of times the fecula was washed, the purer it would be."