spaciousness(n = noun.attribute) capaciousness, commodiousness, roominess - spatial largeness and extensiveness (especially inside a building); "the capaciousness of Santa's bag astounded the child"; "roominess in this size car is always a compromise"; "his new office lacked the spaciousness that he had become accustomed to"
is a kind of bigness, largeness
has particulars: airiness, seating capacity
Derived forms adjective spacious₂, adjective spacious₁