｢楽｣は英語でどう表現する？【単語】ease...【例文】This medicine will give you immediate relief...【その他の表現】comfort... - 1000万語以上収録！英訳・英文・英単語の使い分けならWeblio英和・和英辞書
There is a neighborhood in Tokyo called 有楽町 or Yurakucho, which means “place to have fun” or “entertainment district”. (This is similar to the use of the name 永乐路 or Yongle Road (road of eternal happiness) for a road in China.)
If you look at the oldest character forms currently available to us today, you might be able to make a decent educated guess as to the origin, but to state a character etymology as if it is an incontrovertible fact is irresponsible.
(Obviously, the above does not apply to the small percentage of characters which were created in comparatively modern times and have documented origins.)