valetudinous

As a noun terms

is .

As an adjective valetudinous is

(obsolete) valetudinarian; infirm, sickly.

As adjectives the difference between sickly and valetudinous

is that sickly is frequently ill; often in poor health; given to becoming ill while valetudinous is valetudinarian; infirm, sickly.

As a verb sickly

is to make sickly.

As an adverb sickly

is in a sick manner.

As adjectives the difference between infirm and valetudinous

is that infirm is weak or ill, not in good health while valetudinous is (obsolete) valetudinarian; infirm, sickly.

As a verb infirm

is to contradict, to provide proof that something is not.

As adjectives the difference between valetudinarian and valetudinous

is that valetudinarian is sickly, infirm, of ailing health while valetudinous is (obsolete) valetudinarian; infirm, sickly.

As a noun valetudinarian

is a person in poor health or sickly, especially one who is constantly obsessed with their state of health.