| Word | Definitions | Synonyms |
|---|---|---|
| adiabatic | (adjective) occurring without loss or gain of heat | - |
| adiabaticity | (noun) The condition of occurring without gain or loss of heat (and thus with no change in entropy, in the quasistatic approximation). | - |
| adiaphoron | (noun) (Stoic philosophy) a matter having no moral merit or demerit. | - |
| (noun) a religious ceremonial or ritual observance that is held to be an affair of the individual conscience because it is neither forbidden nor enjoined by the scriptures. | - |