chair with a support on each side for arms
"After hours of standing at his desk, he finally collapsed into his comfortable armchair to rest his tired shoulders."
A chair with supports for the arms or elbows.
"After a long day at work, I finally collapsed into the comfortable armchair to relax my tired shoulders."
To create based on theory or general knowledge rather than data.
"The critics accused him of making an armchair diagnosis about the economy without ever looking at the actual financial reports."
Remote from actual involvement, including a person retired from previously active involvement.
"The veteran journalist was criticized for his armchair commentary on the war he never fought in."