Very large or wide (literally or figuratively). / Very great in size, amount, degree, intensity, or especially extent. / (obsolete) Waste; desert; desolate; lonely.

(poetic) A vast space.

(uncountable) The quality of being vast. / (countable) Something vast.

plural of vast

Acronym of visual audio sensory theater. / (ESA, volcanology) Acronym of volcanic ash strategic initiative team.

plural of vastness

(idiomatic) The greatest part of something, to the point where alternatives are nearly irrelevant in size.

Greatly, in a vast manner.

vastness; immensity

(anatomy) One of the great muscles upon the front of the thigh.