1. Occurring ever half hour

1. Every thirty minutes, every half hour

See also: periodic, periodical

• Mt. St. Helens
• Mt. Vesuvius
• mu
• mu-meson
• muadhdhin
• Muammar al-Qaddafi
• Muammar el-Qaddafi
• muazzin
• Mubarak
• much
• much as
• muchness
• mucic acid
• mucid
• muciferous
• mucilage
• mucilaginous
• mucin
• mucinoid
• mucinous
• muck
• muck about
• muck around
• muck in
• muck up