(Hinduism and Buddhism) the effects of a person's actions that determine his destiny in his next incarnation
"After spending years helping the poor, she felt her good karma would ensure a peaceful rebirth."
The sum total of a person's actions, which determine the person's next incarnation in samsara, the cycle of death and rebirth.
"After centuries of meditation on their karma, the monk felt ready to leave the physical world for his next life in samsara."
In plain English: Karma is the idea that your actions eventually lead to similar consequences for you later on.
"I believe that karma means you get back exactly what you give to others."
Usage: In everyday conversation, karma refers to the general belief that good or bad deeds lead to corresponding positive or negative consequences for oneself later on. Use this term when discussing cause-and-effect relationships rather than specific religious doctrines about reincarnation.
Borrowed from Sanskrit कर्म (kárma), nom.sg. of कर्मन् (kárman, "act, action, performance"); first attested in English in 1785 in a translation of the Bhagavad Gita by Charles Wilkins.