vasodilation

antonym: vasoconstriction
https://doi.org/10.1351/goldbook.16184
Increase in the caliber of the blood vessels, leading to an increased blood flow.
Source:
PAC, 2007, 79, 1153. (Glossary of terms used in toxicology, 2nd edition (IUPAC Recommendations 2007)) on page 1331 [Terms] [Paper]