crux vs jigsaw

crux

• A puzzle or difficulty. 

• The basic, central, or essential point or feature. 

• The critical or transitional moment or issue, a turning point. 

• The hardest point of a climb. 

• A cross on a coat of arms. 

jigsaw

• A jigsaw puzzle. 

• Something that can be compared to a jigsaw puzzle. 

• A power saw with fine teeth and a narrow blade which can cut curves in wood or metal. 

• To cut something using a jigsaw.