Colloquial description of an item (document, schedule, contract, etc.) that cannot be altered without great effort (and possibly some destructiveness) for one reason or another.

Probably derived from how the ten commandments (Exodus 22:* in your bible) were produced on stone tablets, as it requires effort to modify a document that is etched into stone.

See also set in jello for a good opposite.
Once you sign the contract, the terms are set in stone.
by ke6isf April 6, 2005
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(pertaining to holidays) A promise that absolutely will not be broken, unless it was only made verbally by management, in which case it turns out the fuckers are guaranteed to change it.
You know those holiday dates? You can take them as set in stone.

... about those holidays you booked... you're going to have to come in those days, I don't give a shit what you think.
by ochrann January 10, 2020
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