adj. 1. Happy and without worry.
2. Without due thought or consideration.
“Are you aware the man you’re blithely escorting around our building has a documented history of savage violence against robots?”
“I don’t know what ‘blithely’ means, but I’m gonna go get some coffee.”
From Old English bliþe (kind, cheerful, pleasant), possibly from a root word meaning “to shine.” (That funny letter ‘þ‘ is pronounced ‘th’, by þe way.)
Don’t worry; be blithe.