roundel

noun

1. 圆形图案（或标志）；（飞机的）圆形识别标志
   a round design that is used as a decoration or to identify an aircraft

1. 圆形标志
   A roundel is a circular design, for example one painted on a military aircraft.

noun

1. (heraldry) a charge in the shape of a circle
   1. a hollow roundel

   Synonym:    annulet

2. round piece of armor plate that protects the armpit

3. English form of rondeau having three triplets with a refrain after the first and third