the GNU version of the Collaborative International Dictionary of English
n. The quality of being dilatable, or admitting expansion; -- opposed to contractibility.
The Century Dictionary and Cyclopedia
n. The quality of being dilatable, or of admitting expansion, either by inherent elastic force or by the action of a force exerted from without: opposed to contraclibility.
Word Usage
"When an ossification of the aorta, or of its valves, exists, there will be a resistance to the passage of the blood from the left ventricle, either by a loss of dilatability in the artery, or a contraction of the orifice by the ossified parts."