hemerology

From Ancient Greek ἡμέρᾱ (hēmérā, “day; date”) (a variant of ἦμαρ (êmar, “day”), ultimately from Proto-Indo-European *h₂eh₃- (“be hot, burn”)) + -ology (from Ancient Greek -λογῐ́ᾱ (-logĭ́ā, suffix indicating the study of something, or a branch of knowledge), from λόγος (lógos, “word; explanation; subject matter”) (from λέγω (légō, “to arrange, put in order”), from Proto-Indo-European *leǵ- (“to gather”)) + -ίᾱ (-íā, suffix forming a feminine abstract noun) (ultimately from Proto-Indo-European *-i-eh₂ (suffix forming a collective noun))).

来源：wiktionary