Age Invisible

From Pluralpedia, the collaborative plurality dictionary
age invisible (adj.)
Applies toheadmates

Age invisible refers to a headmate whose age is not visible or which does not conform with standardized age measurements. This may show that the headmate does not have age or that time, in the headspace, does not affect them.

Age-invisible headmates are often either nonhuman or developed from childhood trauma (traumagenic). A host may also age dissociate to the point of 'losing' their age.