المعنى الاصطلاحي :

Anything people who are competent for religious duties according to the Shariah say, do, or believe.

الشرح المختصر :

"Af‘āl al-mukallafeen" (deeds of the liable) refers to all one's sayings, deeds, and beliefs. The most important conditions of "takleef" (liability under the Shariah) are: 1. Knowing what is required. 2. Having the ability to understand the Shariah address. 3. Sanity, i.e. not being mad. 4. Having reached puberty. 5. Having the ability to carry out religious duties. 6. Having the ability to choose, i.e. not being forced.