Wiktionary
sub-rectangular
a. Having an overall rectangular shape, but with rounded edges.(reference-journal late=Griset first=Suzanne title=Requirements for the Preparation of Archaeological Project Collections for Submission to the Arizona State Museum year=2004 page=14 url=http://www.statemuseum.arizona.edu/crservices/reposit/manual.pdf publisher=Arizona State Museum, University of Arizona language=English)