1. Descriptive of being impossible to break or to alter: The rules at school were irrefragable and the students had to obey and abide by them.
2. Relating to something that is impossible to prove as being wrong or false: The fact that people and animals get hungry is an irrefragable truth.

The certainty that snow is white is irrefragable!
3. Etymology: from Latin infringere, "to damage, to break off", from in-, "not" + frangere, "to break".