1. A second conception after a prior one, and before the birth of the first, by which two foetuses are growing at once in the same matrix.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• auperfetation,
• zuperfetation,
• xuperfetation,
• duperfetation,
• euperfetation,
• wuperfetation,
• syperfetation,
• shperfetation,
• sjperfetation,
• siperfetation,
• s8perfetation,
• s7perfetation,
• superefetation,
• superfertation,
• superfettation,
• superfetationn,
• superfetetion,
• Supereffetation,
• Superfeteration,
• Superfation

• superpatriotic,
• superfluity,
• superposition,
• superpatriotism,
• superficial,
• superfecundation,
• superficiality,
• superficies,
• superfecta,
• supervention,
• supervision,
• superfatted,
• superfetate.

The plural of the "superfetation" can be the "superfetations".

The singular of the "superfetation" can be the "superfetation".