Feeling sentimental or emotionally moved, especially about the past or farewells; often used as a na-adjective in Japanese.
昔の写真を見て、ちょっとセンチメンタルな気分になった。
I looked at old photos and felt a bit sentimental.
あの映画は音楽が美しくて、観客をセンチメンタルにさせる。
That movie's music is beautiful and makes the audience feel sentimental.
別れの季節になると、いつもセンチメンタルな歌をよく聴く。
When it's farewell season, I often listen to sentimental songs.