Apunya is the fruit of bad or improper deeds in Hinduism. Every human being is observed to undergo, the experience of opposites in life, called the dvandavas in yoga, such as sukha and duhkha (pleasure and pain); usna and sita (hot and cold); kathora and mridu (hard and soft); prapto and aprapti (achievement and failure); labha and hani (gain and loss) and so on.
Punya and papa (merit and demerit) and also form a set of opposites
which are encountered in life by all of us. It is said in Yogasutra of
Patanjali (IV:7) that various deeds we perform in life are of three kinds:
punya karma or shukla karma (meritorious deeds), krishna-karma (black deeds), and
ashukla akrishna karma (neutral deeds).
All deeds except the punya karma are called apunya karma in
Yoga. Patanjali has explained that every karma done by us bears its fruit in
this or the next birth (II: 12-14). Pleasurable fruits arise out of punya
karmas, while apunya karmas result from pain and sorrow (II:12). These karmas
decide the jati (species into which one shall be born), ayu (the length life),
and bhoga (experience) (II:13). He further says that pleasurable and painful
fruit arise from the punya and apunya karmas respectively (II:14). He has said
further (Yogasutra II:15) that an adept of Yoga (vivekin) looks upon all
experiences as essentially painful and so he/she strives to be freed from them
forever, in the state of kaivalya.
In the Bhagavad Gita (IV.22), the state of being free of the dvandvas or opposites, i.e., having an attitude of samatva (equanimity) towards siddhi or asiddhi (achievement or failure), is said to be the specialty of a yogin.