MEANING: noun:
1. A mound of earth placed over prehistoric tombs. Also known as a barrow.
2. A dome-shaped swelling formed in cooling lava.

ETYMOLOGY: From Latin tumere (to swell). Earliest documented use: 1686.

RUMULUS - the founder of Rome who liked to drink

TUMBULUS - acrobatic

TUMULUST - the state of arousal accompanying an erection

TUTULUS - a tiny Pharaoh

(sorry, the list started shorter, but it just grew and grew...)