This may be a feminine form of Ron. It is also spelled Ronda. That might explain why it's a recent name. As people had fewer children and not necessarily any sons, they could name a daughter for her dad, Ron. Maybe at least sometimes that is the case for names like Leslie and Beverly that were also men's names at one time.
In 2018, 45 is the most common age for an American (U.S.) Rhonda who is registered female with the Social Security Administration. It is the 272nd most common female first name for living U.S. citizens.
― Anonymous User 10/17/2018
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The name Rhonda was given to 18 girls born in the US in 2015.