階級 means class, rank, or grade in various hierarchies.
SOCIAL CLASS:
MILITARY RANKS:
- 将校階級: officer ranks
- 下士官階級: non-commissioned officer ranks
- 階級章: rank insignia
SPORTS (WEIGHT CLASS):
- ボクシングの階級: boxing weight class
- ヘビー級: heavyweight
- ライト級: lightweight
- 階級を上げる: to move up a weight class
RELATED WORDS:
- 等級: grade, class, rank
- 身分: social status
- ランク: rank (loanword)