1. Of or relating to or resembling a comet
   - cometary

See also: comet

• family Aplodontiidae
• family Aplysiidae
• family Apocynaceae
• family Apodidae
• family Apogonidae
• family Apterygidae
• family Aquifoliaceae
• family Araceae
• family Araliaceae
• family Araucariaceae
• family Arcellidae
• family Arcidae
• family Arctiidae
• family Ardeidae
• family Arecaceae
• family Argasidae
• family Argentinidae
• family Argiopidae
• family Argonautidae
• family Ariidae
• family Aristolochiaceae
• family Armadillidiidae
• family Artamidae
• family Ascaphidae
• family Ascaridae