Said to wish a final farewell; goodbye.

A farewell, a goodbye; especially a fond farewell, or a lasting or permanent farewell.

neither harmful nor beneficial

Theologically indifferent.

The belief that certain religious doctrines or ceremonies are indifferent, i.e. do not matter.

One who believes in adiaphorism.

plural of adiaphoron / (nonstandard, uncommon) in singular use

(philosophy) A matter that is morally neutral. / (theology) Something neither forbidden nor commanded by scripture.

(physics, thermodynamics, of a process) That occurs without gain or loss of heat (and thus with no change in entropy, in the quasistatic approximation).

An adiabatic curve or graph