Ampleness

fully sufficient or more than adequate for the purpose or needs; plentiful; enough:
an ample supply of water; ample time to finish.
of sufficient or abundant measure; liberal; copious:
an ample reward.
of adequate or more than adequate extent, size, or amount; large; sp-cious; roomy:
ample storage sp-ce.
historical examples

the parterre, extending before the main building, is of an ampleness scarcely conceivable until once viewed.
royal palaces and parks of france milburg francisco mansfield

then comes the new property of the university of pittsburgh, which is built with ampleness of design.
charities and the commons: the pittsburgh survey, part ii: the place various

there was much of the ampleness of mirabeau, but no heaviness; there was so much soul that this carried that lightly.
balzac frederick lawton

adjective
more than sufficient; abundant: an ample helping
large in size, extent, or amount: of ample proportions
adj.

mid-15c., from middle french ample, from latin amplus “large, sp-cious,” related to ampla “handle, grip.”