late 13c., from O.Fr. cours, from L. cursus "a running race or course," from curs- pp. stem of currere "to run" (see current). Most extended senses (meals, etc.) are present in 14c. Academic meaning "planned series of study" is c.1600 (in French from 14c.). The verb is from 16c.
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with of course
In the customary or expected order, naturally, as in The new minister did not, of course, fire the church secretary. This usage, first recorded in 1548, employs course in the sense of “ordinary procedure.”
Certainly, as in Of course I'll answer the phone, or Are you going to the meeting?—Of course.
[ Early 1800s