Breakthrough and Milepost

Breakthrough noun - An instance of notable progress in the development of knowledge, technology, or skill.

Milepost and breakthrough are semantically related In some cases you can use "Milepost" instead a noun "Breakthrough".

Milepost noun - A point in a chain of events at which an important change (as in one's fortunes) occurs.

Breakthrough and milepost are semantically related in achievement topic. Sometimes you can use "Breakthrough" instead a noun "Milepost".