What does "act of congress" mean?

A statute enacted by the United States Congress.

What is a synonym for "act of congress"?

Common synonyms include: federal act.

noun, slang

noun, slang ·Uncommon ·College level

Noun

1
A statute enacted by the United States Congress. US, literally
2
An authorization that is extremely difficult to obtain, especially in a timely fashion. US, colloquial, idiomatic
"Does it take an act of Congress just to get a stop sign on a corner?"

"Does it take an act of Congress just to get a stop sign on a corner?"

From the literal sense of act (“legislation”) enacted by US Congress.