basic, critical, crucial, decisive, essential, fundamental, important, key, main, major, necessary, principal, significant, vital
dominant
Fear was the dominant element in the child's decision to skip school that day.
considerable, large
Working in construction always involved a large element of risk that we had to accept.
competitive
The game had a strong competitive element that kept all the players excited until the end.
racial, sexual
There was a sexual element to their disagreement that made the conversation uncomfortable.