Indicating that someone or something appears lonely or sad; the suffix -げ expresses an appearance or seeming quality (i.e., 'looks lonely').
彼は一人で窓の外を見て、寂しげな顔をしていた。
He was looking out the window alone with a lonely expression.
雨の日は街全体が寂しげな雰囲気になる。
On rainy days, the whole town takes on a somewhat lonely atmosphere.
彼女は声を震わせながら、寂しげに笑った。
She smiled faintly, sounding a little lonely as her voice trembled.
古い家の庭に咲く花が、どことなく寂しげに見えた。
The flowers blooming in the old house's garden somehow looked lonely.