modus


modus
modus (n.) "way in which anything is done," 1640s, from L. modus (pl. modi), lit. "a measure, extent, quantity; manner" (see MODE (Cf. mode) (n.1)). Especially in MODUS OPERANDI (Cf. modus operandi) and MODUS VIVENDI (Cf. modus vivendi).

Etymology dictionary. 2014.