Sacred

adjective
1.
devoted or dedicated to a deity or to some religious purpose; consecrated.
2.
entitled to veneration or religious respect by association with divinity or divine things; holy.
3.
pertaining to or connected with religion (opposed to secular or profane):
sacred music; sacred books.
4.
reverently dedicated to some person, purpose, or object:
a morning hour sacred to study.
5.
regarded with reverence:
the sacred memory of a dead hero.
6.
secured against violation, infringement, etc., as by reverence or sense of right:
sacred oaths; sacred rights.
7.
properly immune from violence, interference, etc., as a person or office.
adjective
1.
exclusively devoted to a deity or to some religious ceremony or use; holy; consecrated
2.
worthy of or regarded with reverence, awe, or respect
3.
protected by superstition or piety from irreligious actions
4.
connected with or intended for religious use: sacred music
5.
dedicated to; in honour of

jargon
Reserved for exclusive use by something. The term might mean only writable by whatever it is sacred to.
For example, “Register 7 is sacred to the interrupt handler” would mean that if any other code changed the contents of register 7, dire consequences would ensue.
[Jargon File]
(2002-12-30)