Downcast and Low-down

Downcast adjective - Directed down.

Low-down and downcast are semantically related In some cases you can use "Low-down" instead an adjective "Downcast".

Low-down adjective - Not following or in accordance with standards of honor and decency.

Downcast and low-down are semantically related in depressed topic. Sometimes you can use "Downcast" instead an adjective phrase "Low-down", if it concerns topics such as terrible, discouraged.