heavyweight

Short definition from Wiktionary

Noun

1. 1
   A very large, heavy, or impressive person.
2. 2
   The professional boxing weight class for boxers weighing more than 190 pounds; a boxer in that division.
3. 3
   A similar division and contestant in other sports.

Adjective

1. 1
   Of the heavyweight boxing (or similar) division.
2. 2
   Being relatively heavy.
3. 3
   Being a leader in one's field.
4. 4
   Important or impressive.