"fecal discharge from a newborn infant," 1706, from Latin meconium "excrement of a newborn child," literally "poppy juice," from Greek mekonion "poppy-juice, opium," diminutive of mekon "poppy" (perhaps cognate with Old Church Slavonic maku, German Mohn "poppy"). So called by classical physicians for its resemblance. Related: Meconial.
meconium me·co·ni·um (mĭ-kō'nē-əm)
A dark green fecal material that accumulates in the fetal intestines and is discharged at or near the time of birth.