"Tight lipped" means someone is not saying much about a certain thing.
Example:
The police have been very tight lipped about the details of the crime.
aghast....taken aback....tight-lipped...
Calvin Coolidge
Tight-lipped can be positive or negative. It means the person keeps what they know to themselves, which is often good, but can be bad.
Only they know. The military is a pretty tight lipped group of people.
"Schtum" is a slang term that originates from Yiddish, and it means to be silent or keep quiet. It is often used in British English to indicate someone is being tight-lipped or unwilling to speak.
The closer they got to the office, the more tight lipped he became.
The closer they got to the office, the more tight lipped he became.
RFP is not an idiom. It's an abbreviation.
It's not really an idiom. It means "what are you thinking about."
It is not an idiom, it means your nose is itching.
Blue-lipped is an adjective, a word that describes a noun. Example: a blue-lipped corpse.
idiom means expression like a page in a book