"one who rules," late 14c., agent noun from rule (v.). Meaning "instrument used for making straight lines" is c. 1400 (compare rule (n.)).
rugrat
ruin
ruination
ruinous
rule
ruler
ruling
ruly
rum
rumba
rumble
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}