unworth
Not worth; not deserving of.
rare
This was rather pleasant, for she had to give Peter her hand, and so life became less unworth living to Peter.
Where it comes from
From Middle English unworth, unwurth, from Old English unweorþ, unweorþe (“unworthy, poor, mean, of low estate, worthless, contemptible, ignoble”), equivalent to un- + worth.
Adapted from the Wiktionary entry unworth (CC BY-SA 4.0).