Slang term, often used for men with long hair, sometimes with a slightly derogatory or joking tone.
あのバンドのギタリスト、ロン毛がトレードマークだよね。
That band's guitarist's long hair is his trademark, isn't it.
ロン毛の男が急に増えた気がする。
It feels like guys with long hair have suddenly increased.
Katakana-only spelling; common in casual writing.
Abbreviation of ロングヘア (long hair) with 毛 (hair) replacing ヘア, creating a slangy compound.