objeto, m., object.
obligación, f., duty, obligation.
obligar, to oblige, compel.
obra, f., work; poner por obra, to carry out, execute.
obscurecer(se), to darken, grow dark.
obscuridad, f., darkness, obscurity.
obscuro -a, dark.
obsequiar, to treat, present, regale; obsequiar con regalos, to make presents.
obsequio, m., gift; en obsequio de, for the sake of.
observar, to observe.