methodology n.

early 15c., "regular, systematic treatment of disease," from Latin methodus "way of teaching or going," from Greek methodos "scientific inquiry, method of inquiry, investigation," originally "pursuit, a following after," from meta "in pursuit or quest of" (see meta-) + hodos "a method, system; a way or manner" (of doing, saying, etc.), also "a traveling, journey," literally "a path, track, road," a word of uncertain origin (see Exodus).

Meaning "any way of doing anything, orderly regulation of conduct with a view to the attainment of an end" is from 1580s; that of "orderliness, regularity" is from 1610s. Meaning "a system or complete sent of rules for attaining an end" is from 1680s. In reference to a theory of acting associated with Russian director Konstantin Stanislavski (1863-1938), it is attested from 1923.

word-forming element indicating "branch of knowledge, science," now the usual form of -logy. Originally used c. 1800 in nonce formations (commonsensology, etc.), it gained legitimacy by influence of the proper formation in geology, mythology, etc., where the -o- is a stem vowel in the previous element.

The second element is prop[erly] -logy (-logue, etc.), the -o- belonging to the preceding element; but the accent makes the apparent element in E[nglish] to be -ology, which is hence often used as an independent word. [Century Dictionary] 

"of or pertaining to methodology," 1828, from methodology + -ical. Related: Methodologically.