Akusala, in brief, means the ten kinds of duccaritas. These are:

(1) Panatipata - Taking the life of another being, i.e. killing.
(2) Adinnadana - Taking a thing or property which is not given by the owner, i.e. stealing or robbing.
(3) Kamesu-micchacara - Sexual immorality, i.e. unlawful indulgence in sensual pleasures (kamaguna).

These are the three immoral physical actions or conduct - 'kayakammam'.

(1) Musavada - Telling lies or falsehood the offence of lying.
(2) Pisunavaca - Backbiting or slanderous talk.
(3) Pharusavaca - Using abusive language, or harsh language, or obscene words.
(4) Samphappalapa - Frivolous talk.

The above are the four verbal acts of misconduct called 'vacikamma'.

(1) Abhijjha - Covetousness, i.e. to plan or imagine wrongfully with avarice to get possession of others' property and wealth.
(2) Byapada - The offence of 'ill-will', i.e. plotting others' death or destruction with an intention of doing harm.
(3) Micchaditthi - False view, or rather, having a wrong conception of not believing that there is the Law of Kamma by which benefits will be accrued.

These three enumerated above, are caused by the mind - 'manokamma'.

As mentioned in the foregoing, there are ten duccaritas - evil or sinful immoral actions on which no reliance should be made. Moreover, these should also be avoided. More details relating to these ten duccaritas may be referred to in the Sallekha Sutta Dhamma, if desired. Putting it in a nutshell, all actions relating to thought, word or speech, and deeds (physical) which cause misery and sufferings to others are akusala that should be kept away as being unreliable.