Quarterfinal groups, e.g.

• Candles in a menorah, e.g.
• Quartets times two
• Planets and notes in the musical scale
• Day in Ascot rearranged for groups of eight
• Bytes, usually
• Pairs of quartets
• Wild coast hiding first sign of danger for boat crews?
• Series of eight

Wiktionary Word definitions in Wiktionary
n. (plural of octad English)