The term "incapacious" refers to something that is inadequate or lacking in space, capacity or size. The antonyms for this word are plentiful, expansive, roomy, ample, capacious, and spacious. A plentiful space is one that is abundant and generous. Expansive refers to something that is widespread or broader. Roomy signifies a place with much free space, while ample means sufficient and relatively large. Capacious is a synonym for spacious and refers to a large area or container that can accommodate many things. In short, these antonyms are opposites of the term "incapacious," as they describe things that are abundant, wide, or large in size.