moderately good luck
Used in fortune-telling contexts, especially on omikuji (おみくじ) fortune slips at shrines and temples. Ranks between 小吉 (small luck) and 大吉 (great luck).
See also: おみくじ
I drew an omikuji and got moderately good luck.
Generic 'good luck' category; 中吉 is a specific grade within it.
Compound of 中 (middle, moderate) and 吉 (good luck). The exact historical origin of the omikuji ranking system is uncertain.