A variant would be monocephalous:
- Having only one head; in botany, bearing a single capitulum or head.
- Specifically, having the character of a monocephalus.
or monocephalus:
– noun
- In teratol., a double monster having only one head but two bodies. Also called syncephalus.
See also syncephalus:
– noun
- In teratology, a double monster with more or less fusion of the heads: same as monocephalus.