The Collaborative International Dictionary
rhabdology
Rabdology \Rab*dol"o*gy\ (r[a^]b*d[o^]l"[-o]*j[y^]), n. [Gr. "ra`bdos rod, stick + -logy: cf. F. rabdologie.] The method or art of performing arithmetical operations by means of Napier's bones. See Napier's bones. [Written also rhabdology.]
Wiktionary
rhabdology
n. A variant spelling of '''rabdology'''.