To have a blow is to have an attack on ones situation or being.
"what you did was a big blow to my relationship"
"I didn't mean it as a blow."
A rest or break- used by Southern football coaches. Somewhat archaic.
Joe! Get in there and give Terry a blow at linebacker. He's missed three tackles in a row.
(n.) A defeat, loss, reduction or failure, especially of a severe or devastating nature. This term is optionally preceded and/or followed by the prepositions "to" and/or "from", which can be used to further refine its scope of meaning.
1. It has been over two months since the team's last win, so the coach's job may be at risk if they suffer another blow this Saturday.
2. In their currently weakened state, a blow from the north may be enough to destroy the army's 3rd division.
3. While the demotion had no meaningful impact on his salary, it was certainly a blow to his ego.