The Collaborative International Dictionary of English v.0.48:

Marginalia \Mar`gi*na"li*a\, n. pl. [NL.]
   Marginal notes.
   [1913 Webster]

WordNet (r) 3.0 (2006):

marginalia
    n 1: notes written in the margin

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "marginalia":
   adversaria, affix, aide-memoire, allonge, annotation, appendix,
   coda, codicil, commentary, docket, enclitic, entry, envoi,
   epilogue, footnote, infix, interlineation, interpolation, item,
   jotting, marginal note, memo, memoir, memorandum, memorial,
   minutes, notation, note, postscript, prefix, proclitic, register,
   registry, reminder, rider, scholia, scholium, suffix, tail