丧 (sàng): To lose, to forfeit, to die. Here it means a complete and total loss.
尽 (jìn): To exhaust, to use up entirely, to the utmost limit. It emphasizes the completeness of the loss—nothing is left.
天 (tiān): Heaven, sky, or nature. In this context, it refers to that which is innate, natural, and endowed by a higher order.
良 (liáng): Goodness, virtue, conscience. The character itself depicts a good quality.
The characters combine to create a vivid image: “to lose completely (丧尽) the conscience given by Heaven (天良).” The term `天良 (tiānliáng)` itself is a word for “conscience,” viewed in traditional Chinese culture as an inborn moral compass. Therefore, to `丧尽天良` is to utterly obliterate this fundamental aspect of one's humanity.