Correct spelling for the English word "Acronyc" is [ˈakɹənˌɪk], [ˈakɹənˌɪk], [ˈa_k_ɹ_ə_n_ˌɪ_k] (IPA phonetic alphabet).
In astron., a term applied to the stars when they either appear above or sink below the horizon at the time of sunset.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.