1. (表示方位的)标记，路标，记号;（起提示作用的）标示物
A marker is an object which is used to show the position of something, or is used to help someone remember something.

2. （品质或特点的）标志，代表
If you refer to something as a marker for a particular quality or feature, you mean that it demonstrates the existence or presence of that quality or feature.

3. 记号笔，毡笔(笔头较粗，由毡毛制成，用于绘画和着色)
A marker or a marker pen is a pen with a thick tip made of felt, which is used for drawing and for colouring things.

1. some conspicuous object used to distinguish or mark something

e.g. the buoys were markers for the channel

2. a writing implement for making a mark

3. a distinguishing symbol

e.g. the owner's mark was on all the sheep

Synonym: markingmark