Indigestion; a medical condition in which the stomach has difficulty digesting food.
昨夜脂っこい物を食べ過ぎて、朝から消化不良で気分が悪い。
I ate too much greasy food last night and have felt unwell with indigestion since morning.
医者に行ったら消化不良だと言われ、消化薬を処方された。
The doctor said it was indigestion and prescribed digestive medicine.
飲みすぎは消化不良の原因になるので注意したほうがいい。
Drinking too much can cause indigestion, so you should be careful.
Figuratively, an inability to digest information — lacking comprehension; half-understood or poorly assimilated knowledge.
授業で説明が速すぎて消化不良になった。復習が必要だ。
The lecture went too fast and I couldn't digest it — I need to review.
本を読んだだけでは消化不良になりがちなので、問題を解いて定着させよう。
Just reading a book often leads to poor understanding; solve problems to solidify it.