superheavy

Short definition from Wiktionary

Adjective

1. 1
   Much heavier than usual.
2. 2
   Much heavier than usual: Describing a transuranic element with an extremely high atomic number; typically taken to mean beyond lawrencium (element 103, the last actinide).
3. 3
   stressed more than is usual

Noun

1. 1
   A superheavy thing.
2. 2
   A superheavy thing: A superheavy element.
3. 3
   A superheavy thing: A superheavy tank or artillery piece.