lower vs retard

To fall; to sink; to grow less; to diminish; to decrease 

To decrease in value, amount, etc. 

To reduce operations to single machine instructions, as part of compilation of a program. 

To reduce the degree, intensity, strength, etc., of 

To bring down; to humble 

(lower oneself) To humble oneself; to do something one considers to be beneath one's dignity. 

To let descend by its own weight, as something suspended; to let down 

To reduce the height of 

To depress as to direction 

to pull down 

To reduce (something) in value, amount, etc. 

To make less elevated 

To decelerate; to slow down. 

To put off; to postpone. 

To keep delaying; to continue to hinder; to prevent from progressing.