The property of being reliable, reliability.(noun)
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Use "reliableness" in a sentence
"Of course, these proxies for reliableness - links, market evaluation, geographic proximity - wouldn't be perfect."
"There can be no reliableness of character without repose."
"He explained how he arrived at this estimate, the reliableness of which is beyond dispute, though it may seem incredible to those who have not been in southern seas during the season when the sooty petrels"