circular letter; circulating document
Refers to a document or letter circulated among a group, often for official or organizational communication.
The neighborhood association's circular letter informed us of next month's cleaning duty.
A circular was circulated to all employees from the company.
palindrome
A word, phrase, or sequence that reads the same forwards and backwards, e.g., しんぶんし (新聞紙).
"Takeyabu yaketa" (the bamboo grove burned) is a famous palindrome.
Variant kanji form using 廻; less common than 回文.
From 回 (kai, 'circulate') + 文 (bun, 'writing'). The palindrome sense likely derives from the idea of a sentence that 'circulates' back to its start.