Overmuch and Overboard

Overmuch adjective - Going beyond a normal or acceptable limit in degree or amount.

Overboard and overmuch are semantically related in excessive topic. In some cases you can use "Overboard" instead an adjective "Overmuch".

Overboard adverb - To extremes.

Overmuch and overboard are semantically related in extravagant topic. Sometimes you can use "Overmuch" instead an adjective "Overboard", if it concerns topics such as excessive, overdone.