constant
/ˈkɒnstənt/·컨스턴트·adjective
occurring continuously; unchanging
LatinCEFR B2
Root
Latin 'con-' (together) + 'stare' (to stand)
Latin constans (standing firmly together) → Old French constant → English constant (14th c.)
In a word
Latin con- (together) + stare (to stand). 'Standing together' = unwavering. In mathematics a constant is 'a number that always stands' — constant (unchanging), constantly (continually), constancy (steadfastness), inconstant (fickle = not standing together). A person's loyalty and a mathematical constant are the same word — for Latin, both are 'standing together'.
Examples
He was a constant source of support.
The temperature remained constant.
Pi is a mathematical constant.
Related
constantlyconstancyinconstantconsiststable