na-adjective, noun
unfeeling; heartless; cold-hearted
Describes a person or attitude lacking warmth, sympathy, or compassion; often used to criticize someone's cold behavior.
彼は薄情な態度をとった。
He took a cold-hearted attitude.
そんな薄情なことを言わないで。
Don't say such heartless things.
Compound of 薄 (thin, light) and 情 (emotion, feeling), literally 'thin feelings', conveying a lack of deep emotional warmth.