Is there a term for the feeling that an object does not weigh enough?

single-word-requests

When I handle small objects, if they don't weigh as much as my brain thinks they should I sometimes get the impression that they are low quality and perhaps cheap.

I believe a term that might be used when they have sufficient weight is 'gravitas'. Is there a similar term for the opposite, when something lacks sufficient substance, weight or gravitas?

The latin root of 'Gravitas' is 'gravis' meaning heavy, serious, troublesome, hard or grave. "Gravitas" conveys an impression of seriousness, weight or importance. The word I am looking for would similarly convey an impression of a lack of substance, lack of heft, insignificance, triviality, paltriness or unimportance.

One might say that the device feels "slight". This sense of the word is defined by Merriam-Webster as "deficient in weight, solidity, or importance".

When you pick up an object that feels solid and substantial, a somewhat common idiom would be "Feel the heft!". Conversely, if something is lighter in weight than expected, it can be said to "lack heft".

Definition of "heft" from Google dictionary:

the weight of someone or something.

synonyms: weight, heaviness, bulk "the heft of the urn surprised us"

I think chintzy is the best word for what you describe:

From Merriam-Webster:

poorly or cheaply done or made : of low quality

Since you're looking for an antonym to gravitas here are some:

triviality

Oxford dictionaries

1: Lack of seriousness or importance; insignificance:

the mediocrity and triviality of current popular culture

trifling

dictionary.com

of very little importance; trivial; insignificant:

of small value, cost, or amount: a trifling sum.

frivolous; shallow; light:

insubstantial

Oxford learner's dictionaries

not very large, strong or important

lightweight

dictionary.com

being lighter in weight, texture, etc., than another item or object of identical use, quality, or function:

a lightweight topcoat; a lightweight alloy for ship construction.

weightless

dictionary.com