Definition of valetudinarian:

part of speech: noun

A person of weak or sickly constitution.

part of speech: adjective

Sickly; seeking to recover health.

Usage examples:

• They began to think me some poor valetudinarian but though I was in torments, a feeling of vanity made me endeavour to behave sensibly. Jacques Casanova de Seingalt in "The Memoires of Casanova, Complete The Rare Unabridged London Edition Of 1894, plus An Unpublished Chapter of History, By Arthur Symons".