"Vessel size" refers to the physical dimensions or capacity of a container or vehicle used for holding or transporting something. It describes how big or small a specific vessel is. Full definition
(c) Quantification of vessel size of CD31 - stained tumour vessels in Tie2PEKO mice normalized to WT average. (nature.com)
In the past decade vessel size has grown exponentially creating a new class of container ships known as ULCVs (Ultra Large Container Vessel) with a 10,000 to 20,000 container capacity. (globaltrademag.com)