optimus, comp., [72].
optō, w. subst. cl. developed from optative, [296], 1.
optumus, spelling, [9], 1.
opus est, w. abl., [218], 2;
—— w. partic., [218], 2, c.
-or, nouns in, [34];
—— -or for -os, [36];
—— gender of nouns in, [43], 1;
—— exceptions in gender, [44], 2;
—— as suffix, [147], 2.