Thug and Yardbird

Thug noun - A violent, brutal person who is often a member of an organized gang.

Yardbird and thug are semantically related In some cases you can use "Yardbird" instead a noun "Thug".

Yardbird noun - A military recruit who is assigned menial tasks.

Thug and yardbird are semantically related in person who breaks the law topic. Sometimes you can use "Thug" instead a noun "Yardbird".