幸亏 is a conjunction meaning 'thank goodness' or 'luckily', used to express relief that something undesirable was avoided, often due to timely intervention or fortunate circumstances. The character 幸 (xìng) means 'happiness', 'good fortune', or 'blessing', while 亏 (kuī) literally means 'deficiency' or 'loss' but in this fixed expression functions as a grammatical particle emphasizing the narrowness of the escape — i.e., 'but for the good fortune, there would have been loss'. Together, they convey gratitude for an outcome that narrowly avoided harm or trouble.

This word typically begins a sentence or clause and is followed by a positive result or explanation of why disaster was averted. It carries a tone of sincere relief and is common in spoken and written Chinese across everyday, narrative, and conversational contexts. While it can appear in formal writing, it’s most frequent in informal speech — especially when recounting personal experiences involving near-misses, accidents, or unexpected help.