'Constant' is Latin for 'standing firm' — the same root connects 'cost,' 'stable,' and 'state.'
Occurring continuously over a period of time; unchanging in nature, value, or detail; steadfastly loyal or faithful.
From Latin 'cōnstāns' (standing firm, steady, unchanging), present participle of 'cōnstāre' (to stand together, to stand firm, to be consistent), from 'com-' (together, intensifier) + 'stāre' (to stand), from PIE *steh₂- (to stand). The original sense was physical — standing upright and not falling — which then extended to moral firmness, unchanging nature, and mathematical fixity. The same root 'stāre' produced