oloroso, -a fragrant.
olvidar forget.
olvido m. oblivion, forgetfulness, neglect.
onda f. wave.
ondeante adj. waving, flowing.
ondear wave.
ondina f. undine, water-sprite.
ondular undulate, rise and fall.
onza f. doubloon (former gold coin, = about $16).
ópalo m. opal.