ad. In an immutable manner. In a way that cannot be varied, or changed.
The Century Dictionary and Cyclopedia
In an immutable manner; unchangeably; invariably.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
ad. in an unalterable and unchangeable manner
Word Usage
"Because while it may heighten their belief that gender is only a social construct, it would fly in the face of their simultaneously held, contradictory view that one is born and remains immutably woman (or man)."