Antonym for "Dense" [closed]

I feel like there is no perfect word to describe the opposite of "dense." Density as in mass divided by volume.

All I can think of are words like "light," "fluffy," or "sparse" that aren't exactly what I am trying to say when describing something that has a large volume, but not a lot of mass.

Of all the bowling balls he preferred the [not dense] ones because throwing them down the alley fast made him feel cool.

A historical word to mean the opposite of dense was rare, as stated in the following taken from an article in DON'T LOOK NOW IT'S DEVAN GOLDSTEIN:

Once upon a time, though, dense had an opposite. Until the mid-19th century, the word was rare.

In fact, the earliest meaning of rare in English was precisely this one. The OED notes the word’s meaning as “[o]pposed to dense,” and provides the following example (from around 1420), among others: The londis fatte, or lene, or thicke, or rare.

Also, a check of current dictionary definitions gives us this one from Merriam-Webster:

rare: marked by wide separation of component particles; thin (e.g. rare air)

So, rare does seem to be used for "objects of low(er) density" in the physics sense of the word. This is because typically when we think of "dense" we think of "heavy", but in the pure physical world this in not the case as weight is subjective, while (as you mentioned) mass and volume are not.

Now the caveat to all this, is that the usage of word this way in now rare itself (pun intended). It quite possible that you will get a odd look or be misunderstood if you ask for a "rare bowling ball".

"Of all the bowling balls, he preferred the lighter ones because throwing them down the alley fast made him feel cool."

Light — M-W

adj. 1.a. having little weight; not heavy

Bowling ball terminology says POROSITY

http://www.bowlingthismonth.com/bowling-balls/

And throw a ball is most likely a NO NO. I believe the term is to HOOK a ball....

You might want to look into dynamic in this text, too: https://bowler2bowler.wordpress.com/2011/02/02/bowling-ball-terminology-maintenance-by-james-goulding-iii/

This question asks for a word "describing something that has a large volume, but not a lot of mass" - yet gives an example of two small dense objects (bowling balls) with relatively modest variation in weight. This might be making it harder to see what an appropriate antonym of "dense" might be. Some different examples might be useful…

Compare the air at sea level with the air at the top of Everest: the latter, being less dense, is rarified.

Compare a party balloon filled with water and a party balloon filled with helium: water is denser than helium, so the helium balloon is light.

Note that density (mass per unit volume) is not the same as weight or heaviness: in an inertial environment (e.g. Space Station), both granite and pumice are weightless, so the term "light" is really just our layperson's way of comparing the mass of different objects.

Compare a piece of granite with a piece of pumice: apart from being "light", the latter is porous.

Compare the Moon with a white dwarf star (both are about the same size, but the white dwarf has roughly the same mass as the Sun): the Moon is less massive.