Front line and Proscenium

Front line noun - The leading or most important part of a movement.

Proscenium and front line are semantically related in forward topic. In some cases you can use "Proscenium" instead a noun phrase "Front line".

Proscenium noun - The part of a modern theater stage between the curtain and the orchestra (i.e., in front of the curtain).

Front line and proscenium are semantically related in forward topic. You can use "Front line" instead a noun "Proscenium".