[ ˌsu:pəfi:'teɪʃ(ə)n ]
■ noun
1》 Medicine & Zoology fertilization of a second ovum after the start of a pregnancy, leading to fetuses of different ages.
2》 the accretion of one thing on another.
Origin
C17: from Fr. superfétation or mod. L. superfetatio(n-) , from L. superfetare , from super- 'above' + fetus 'foetus'.