Lacking empathy is a term used to describe someone who is unable to understand or share the feelings of another person. This can be due to a lack of understanding, an inability to sympathize, or a lack of compassion. Two words that can be used to describe someone who is lacking empathy are 'HEARTLESS' and 'HARD'. HEARTLESS is an adjective meaning without sympathy or feeling, while HARD is an adjective meaning unyielding or inflexible.