Definition of marginalist in US English:

marginalist

noun

Economics
  • A proponent or adherent of marginalism.

adjective

Economics
  • Of or relating to marginalism or its proponents.

Origin

Early 20th century; earliest use found in The Economic Journal. From marginal + -ist, after marginalism.

Pronunciation

marginalist

/ˈmɑːdʒɪnəlɪst/