0 a serious expression on your face that you use when you do not want someone to know that you think something is funny:
Blake looked ridiculous in leather trousers, and I was desperately trying to keep a straight face.
1 an expression on your face that shows on emotion in order to hide what you really think or feel:
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.