*oler* smell

*olfatear* smell, sniff

*olvidar(se)* forget

*onza* f. ounce

*ópera* f. opera

*opinar* think, judge

*oponer(se)* oppose

*oposición* f. opposition

*opuesto* (pp. of *oponer*) opposed; opposite

*ora* now (used in parallel constructions)