The One who is most steadfast and solid. The One whose strength produces certitude.
“I have only created Jinns and men, that they may serve Me. No Sustenance do I require of them, nor do I require that they should feed Me. For Allah is He Who gives (all) Sustenance, – Lord of Power – STEADFAST (FOREVER).”
(51:56…58) The Holy Quran
From the root m-t-n with the classical Arabic connotations: to be strong, firm, hard to be solid, steadfast, sure the hard outer or apparent part of something elevated and hard ground.