na-adjective, noun
vain; futile; transient; frivolous
Describes efforts, hopes, or things that end up being empty, pointless, or fleeting. Often used in literary or reflective contexts.
彼の努力は徒になった。
His efforts came to nothing.
人生は徒なものだと思うこともある。
Sometimes I think life is a fleeting thing.
無駄 is the common word for 'useless' or 'wasteful' in everyday speech. 徒 is more literary and emphasizes emptiness or transience rather than practical waste.
儚い focuses on the fragility and ephemeral nature of something beautiful or precious. 徒 carries a stronger sense of futility or pointlessness.
The kanji 徒 originally meant 'on foot' or 'follower', but in this reading it is used for its sound to represent the native Japanese word あだ, meaning 'vain' or 'fleeting'. The exact derivation of あだ is uncertain.