Definition of as

• a very poisonous metallic element that has three allotropic forms; arsenic and arsenic compounds are used as herbicides and insecticides and various alloys; found in arsenopyrite and orpiment and realgar
• a United States territory on the eastern part of the island of Samoa
• to the same degree (often followed by `as); "they were equally beautiful"; "birds were singing and the child sang as sweetly"; "sang as sweetly as a nightingale"; "he is every bit as mean as she is"