Person middle?

Yup. I did find it in one reputable online Japanese-English dictionary Jim Breen's WWWJDIC.

Quote:
人中 【じんちゅう】 (n) (1) in company; among people; (2) philtrum (groove in the upper lip that runs from the bottom of the nose to the lip)

Also, if you search on the hanzi/kanji in Google, you'll find discussions of the word as an anatomical term.

Ceci n'est pas un seing.