meconium

noun2

1. •
   A dark green mass, the contents of the fetal intestines during the later stages of mammalian gestation, that forms the first feces of the newborn.

   • The meconium is dark brownish-green in color. The first meconium passed is semi-solid, having been partially dried out in the large intestine. — 1915
2. •
   (no longer used) Opium.