1. Extremely cold
   "gelid waters of the North Atlantic"
   - arctic, frigid, glacial, icy, polar

See also: cold, gelidity

• Protium
• Protium guianense
• Protium heptaphyllum
• proto
• Proto-Indo European
• Proto-Norse
• proto-oncogene
• protoactinium
• protoanthropology
• protoarchaeology
• protoarcheology
• protoavis
• protoceratops
• protocol
• protoctist
• protoctist family
• protoctist genus
• protoctist order
• Protoctista
• protogeometric
• protoheme
• protohemin
• protohippus
• protohistory
• protology