Meaning
Oblivious, inattentive, irrational, or detached from what is happening. Current informal expression; can sound insulting when applied to a person Regional use: United States, later wider English.
Origin
The figurative phrase is an Americanism from the mid-20th century. It extends the literal office notice: someone who is out eating lunch is unavailable to conduct business. A 1946 New Jersey example applies it to a missing sense of humour, and a 1950 Pennsylvania political column uses it for an administration seen as absent from the issue. No more elaborate origin is needed or evidenced.
Research Sources
References used to check this entry’s meaning, history, or documented forms.
Variants
- be out to lunch
- way out to lunch
Usage Examples
- Anyone who thinks that roof will survive another winter is out to lunch.
- I was so tired during the briefing that I was way out to lunch.