In full swing and Stiff-necked

In full swing adverb - Proceeding with full vigor.

Stiff-necked and in full swing are semantically related. In some cases you can use "Stiff-necked" instead an adjective phrase "In full swing".

Stiff-necked adjective - Having a feeling of superiority that shows itself in an overbearing attitude.

In full swing and stiff-necked are semantically related. Sometimes you can use "In full swing" instead an adjective phrase "Stiff-necked".