You can picture rakish as a man who is not tidy and looks all the better for it: the collar open, the hair not combed flat, the hat pushed to one side, and no sign at all that he minds. Under that picture sits an older one — the man who really does live loosely — and the word still carries a little of it.
Wiktionary gives rakish as rake plus -ish, where rake means a man habituated to immoral conduct. So the word began as 'having something of the rake about him', which explains why the stylish sense still carries a faint edge of disrepute.
Wiktionary 記的是 rake 加 -ish，而這裡的 rake 指「習於放浪行徑的男人」。所以這個字一開始就是「帶著那個浪子味」，也就解釋了為什麼今天用來誇人有型時，還隱隱有一點不安分的邊。
Wiktionary entry for 'rakish' (kaikki:3f6f69a190036ae4:1190653807:12898): 'From rake ("man habituated to immoral conduct") + -ish.'
Two branches
歪一點、鬆一點的瀟灑
這一組是今天最常用的：那個浪子的形象只留下外表的部分，變成一種好看的隨性。
adjective · C2
Looking stylish, confident and relaxed in a slightly untidy or daring way. It is used about a man, or about the clothes, hair or manner that give him that look, and it often carries a hint that he does not quite follow the rules.
瀟灑不羈
那個浪子本人
這一支離字源最近：不是「看起來像浪子」，而是真的過著那種日子。來源字典標為 old-fashioned，Wiktionary 標為 dated。
adjective · C2
Used about a man who lives in a wild way: having many sexual relationships, spending his money carelessly, and drinking heavily. This use is old-fashioned and is now met mostly in older novels, films and newspapers.
放蕩的