ectasia (?k?te?z??) or ectasisn (Pathology) pathol the distension or dilation of a duct, vessel, or hollow viscus ec?tatic adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ectasiathe swelling of a hollow organ of the body, as a vein.See also: Disease and Illness-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.