A scream is a loud, sharp noise that people make when they are suddenly scared or hurt. People sometimes scream in excitement too.
You are shy if you are feeling nervous or uncomfortable when you are with other people. A shy person may want to stay quiet or not speak first. People are often shy when they are new to a place, or when meeting strangers.
A smirk is a smile that is smug and slightly offensive. People often smirk at you when they think they know better than you do.
Someone is smug if they are very confident of their ability to do something, but at the same time are calm and complacent about it, as if they can do it very easily.
You are sorry when you have done something that makes you feel bad. You say you are sorry by apologising.
