apyrexia

As a noun apyrexia

is the absence or intermission of fever.

As an adjective afebrile is

having no fever, without a fever.

In medicine terms the difference between apyrexial and apyrexia

is that apyrexial is relating to apyrexy while apyrexia is the absence or intermission of fever.

As an adjective apyrexial

is relating to apyrexy.

As a noun apyrexia is

the absence or intermission of fever.

As nouns the difference between terms and apyrexia

is that terms is while apyrexia is (medicine) the absence or intermission of fever.

In medicine terms the difference between pyrexia and apyrexia

is that pyrexia is fever while apyrexia is the absence or intermission of fever.