- A small yellow-and-black striped beetle(Leptinotarsa decemlineata) that is a major agricultural pest. 科罗拉多薯虫：一种小的黄黑色条纹甲虫（马铃薯叶甲 马铃薯叶甲属） ，为一种主要农业害虫
- Aristotelean
- Aristotelian
- Aristotelian logic
- Aristotelians
- Aristotelic
- Aristotle
- arithmetic
- arithmetical
- arithmetic average
- arithmetic mean
- arithmetic progression
- arithmetics
- arithmetic sequence
- -arium
- -ariums
- Arius
- Arizona
- Arizona College of the Bible
- Arizona College of the Bible
- Arizona State University
- Arizona Western College
- Arjuna
- ark
- Arkansas
- Arkansas Baptist College