From marginal +‎ -ment.

• IPA^(key): /maʁ.ʒi.nal.mɑ̃/

• Audio (France (Vosges)):

  (file)

• Audio (France (Lyon)):

  (file)

marginalement

1. marginally

• “marginalement”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012