blue peter
noun
blue pe·ter
ˈblü-ˈpē-tər 
: a blue signal flag with a white square in the center used to indicate that a merchant vessel is ready to sail
Cite this Entry
“Blue peter.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/blue%20peter. Accessed 31 Oct. 2025.
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