good fortune (esp. omikuji fortune-telling result); good luck; auspiciousness; unspecified day of the month (used to obscure the date a letter, invitation, etc. was written)
Examples (3 in total)
１３日の金曜日は不吉な日だと言われている。
It is said that Friday the 13th is an unlucky day.
４は日本では不吉な数字だ。
Four is an unlucky number in Japan.
彼は１３が不吉な数だという迷信を信じている。
He believes in the superstition that 13 is an unlucky number.