The quality or state of being constant; steadfastness, loyalty, or unchanging nature.
From constant (from Latin constans, from constate 'to stand together, stand firm') + -ness (Germanic suffix creating abstract nouns). The root means 'standing firmly together.'
The Latin root of constantness literally means 'standing firm with something'—it captured an idea of loyalty as literally standing beside someone, which is why it meant both steadfastness and faithfulness.
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