Since at least 1533, irrefragable has been used as an English adjective modifying things (such as arguments or data) that are impossible to refute. It derives from the Late Latin adjective irrefragabilis (of approximately the same meaning), which is itself derived from the Latin verb refragari, meaning "to oppose or resist." Irrefragable rather quickly developed a second sense referring to things (such as rules, laws, and even objects) that cannot be broken or changed. There was once also a third sense that applied to inflexible or obstinate people.