Chapter IV Sloka 07

yda yda ih xmRSy Glain-Rvit -art,
A_yuTwanmxmRSy tdaTman< s&jaMyhm!.

yad˜ yad˜ hi dharmasya 
gl˜nirbhavati bh˜rata | 
tad˜tm˜naÕ s®j˜myaham ( 4|07)||

Whenever there is decline of righteousness, O Arjuna, and rise of unrighteousness, then I manifest Myself.

Dharma is that which sustains and holds together. There is no proper equivalent for this term in the English language. That which helps a man to attain to Moksha or salvation is Dharma. That which makes a man irreligious or unrighteous is Adharma. That which elevates a man and helps him reach the goal of life and attain knowledge is Dharma; that which drags him and hurls him down in the abyss of worldliness and ignorance is Adharma.