I am looking for an antonym for dense in the context of material properties. Specifically, bulk materials which possess negligible porosity, i.e. sound materials.
An example usage sentence might be
Steel is more dense than aluminum, but aluminum is more [_] than steel.
Naturally, one should simply say "less dense" instead of "more [_]" as the former is idiomatic and unambiguous. Still, there is a nagging curiosity of whether such an ideal antonym exists.
Colleagues and I have thought of several candidate words which do not quite have the right meaning, but might be close:
- airy: implies porosity and/or the presence of air
- light: not the correct semantics as this word applies to weight
- sparse: seems to imply atoms are further apart, which is generally not correct (density has little or no correlation with interatomic spacing in homogeneous mono-atomic materials)
and for fun, a made-up word which immediately springs to mind: un-dense.
Are there any superior antonym choices for the desired meaning?