Glossary

Short definitions, written by us, of the terms that appear in the tables and charts on this site. Pick a subject.

• Weather glossary

  The terms that show up in your city forecast, defined one by one, with the official source wherever the term has a standardised definition.

  8 terms

• Everyday astronomy glossary

  The terms in the sunrise, sunset, twilight and moon-phase tables, defined one by one.

  8 terms

• Environment and live-data glossary

  The terms on our earthquake, air-quality, UV and aurora pages, defined one by one, naming the agency that publishes each scale.

  15 terms

• Holidays and calendar glossary

  The terms in our holiday, bridge-day and calendar pages, defined one by one, with the legal source when the term comes from law or convention.

  7 terms

• Saint-of-the-day glossary

  The General Roman Calendar terms that appear on our saint-of-the-day pages, defined one by one.

  8 terms

• Science and space glossary

  The terms from our periodic-table, constant, compound, solar-system and launch pages, defined one by one, with the official source.

  10 terms

• Animals, pets and plants glossary

  The terms from our animal, pet and plant pages, defined one by one, with the source wherever the term has an official reference.

  7 terms

The definitions are ours; where a term has an official definition, the source is named.