A standstill is when something that should be moving has completely stopped. It appears almost always in a small set of phrases — traffic came to a standstill, the talks are at a standstill, production has been brought to a standstill — so learn the phrases, not just the word. Two things make it special. First, it means total stoppage, not slowness: heavy traffic is slow, but traffic at a standstill is not moving at all. Second, it carries the idea that this is wrong — the thing is supposed to be going, and something has jammed it. That is why it is used constantly for traffic, factories, negotiations, and building work, and never for a sleeping cat. Newspapers love it for scale: a strike brings a city to a standstill. In practice it splits into a physical sense (nothing is moving) and a figurative one (no progress is being made), and the same phrases cover both.