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1.
1) A vagina at the margins; 2) an organ that is nearly a vagina.
At first, I couldn't believe that Frank had sex with Larry. But, then I remembered that Larry was a post-op tranny, and so therefore had a marginalia.
by Sam the Word Keeper April 14, 2009
 
2.
Doodles/drawings done in the margin of a notebook.
John: Hey, I saw the marginalia you did in English yesterday. It was pretty good.

Luke: Thanks!
by smileymagicbeth March 19, 2010