From a- +‎ sthenic. By surface analysis, a- (“not”) +‎ sthen- (“strength”) +‎ -ic (“adjective suffix”).

• Rhymes: -ɛnɪk

asthenic (comparative more asthenic, superlative most asthenic)

1. Characterized by, or pertaining to, debility; weak; debilitating.

• asthenia

asthenic (plural asthenics)

1. A person who has asthenia.

• cahnites, chainest, chainset, chanties, teach-ins