rhyme

Definition: identity of some sound in some part, especially the end

Example:brain and gain. 
pledge and ledge. 
flower and power. 
mass and pass and glass and grass. 
game and lame. 
fame and shame. 
smirk and jerk. 
book and took. 

Significance: it adds some rhyme in the end of then poem. this makes poetry better by giving a poem a repetitive quality by sound without repeating a line or phrase in a poem