Rotund means round and plump. A rotund man, rotund and cheerful, a rotund figure.
It is gentler than fat and slightly comic, which is why it belongs to fiction more than to life. Of a voice it means full and rich. Note the Latin rota, a wheel, which is also behind rotate and the rotunda, a round building.
1adjectiverotundRound and plump.
“The rotund little chef patted his belly and laughed.”
2adjectivefullFull and rich in sound.
“The actor's rotund voice filled the whole theatre without a microphone.”
rotund is a quality of shape.
Latin rotundus means round, from rota, a wheel. Rotate and rotunda come from the same wheel.
Latin
rotundus — round
English, today
rotund
Latin rotundus (“round”), from Latin rota (“wheel”), from Proto-Indo-European Hreth₂- (“to run, to roll”).[http://books.google.com/books?id=iuo
Etymology from Wiktionary, CC BY-SA