late 14c., from O.Fr. reguler
, from L.L. regularis
"continuing rules for guidance," from L. regula
"rule," from PIE *reg-
"move in a straight line" (see regent
). Earliest sense was of religious orders (the opposite of secular
). Extended 16c. to shapes, etc., that followed predictable or uniform patterns; sense of "normal" is from 1630s; meaning "real, genuine" is from 1821. Meaning "a regular customer" is recorded from 1852.