triiniodymus

tri·in·i·od·y·mus

(trī-in'ē-od'i-mŭs),
A grossly malformed fetus with three heads, joined at the occiput, and a single body.
[tri- + G. inion, nape of the neck, + didymos, twin]

triiniodymus

(trī″ĭn-ē-ŏd′ĭ-mŭs) [″ + inion, nape of the neck, + didymos, twin]
A deformed fetus with a single body and three heads joined at the occiput.