A keel is the long, heavy beam that runs along the bottom of a boat from front to back, like a spine holding the whole vessel together. The keel does two crucial jobs: it helps the boat stay upright and stable in the water, and it prevents the boat from sliding sideways when the wind pushes against the sails.

Think of it this way: without a keel, a sailboat would tip over easily and drift wherever the wind pushed it, like a leaf floating on a pond. The keel's weight acts like an underwater anchor, keeping the boat balanced even when strong winds fill the sails. On many sailboats, the keel extends down into the water like a fin, giving the boat something to grip against so it can move forward instead of just being blown sideways.

When people say things are on an even keel, they mean everything is steady and balanced, just like a boat with a good keel stays level in rough water. If your week has been on an even keel, nothing too chaotic has happened.

You might also hear that someone keeled over, meaning they suddenly fell down or fainted.