1. synonym of octavo: one-eighth (obsolete)

2. ochavo (a former Spanish coin from the 17th to 19th centuries, notionally equivalent to ⅛ Spanish ounce) (historical)

3. trifle, bauble (anything worthless or useless) (figuratively)

4. octave (a weeklong saint's feast or local party) (Catholicism)

5. octagon (an octagonal building or place) (architecture)