The school uniform is convenient because it can be worn for both informal and formal occasions.
They exchanged formal greetings.
Do we dress formal?
His language is very formal.
Her clothes were out of place at a formal party.
He was a tall, heavy-looking young man of five-and-twenty. His air was grave and stately, and his manners were very formal.
Boy, did she have egg on her face when she showed up at the formal party wearing blue jeans!
I will send our formal agreement to you.
She kept conversation on a formal plane.
Formal dress must be worn.
How formal is this ceremony?
Formal declarations of war haven't been America's style since 1942.
Some cultures and situations are formal, which means that we have to follow rules, other cultures and situations are more informal.
Gift-giving is quite formal in some countries.
Whenever I translate something from English into Spanish, I prefer to use the familiar "tú" instead of the formal "usted".