Never wrong, never missing. If someone has an unerring sense of direction, they always know which way to go — not usually, always. It is a strong, admiring word, and you use it about a skill or an instinct that works every single time: an unerring aim, an unerring eye for detail, an unerring instinct for what an audience wants. It is a bit formal and literary; you meet it in writing and in sports commentary far more than in daily talk. Two things are worth noticing. First, it almost always sits in front of a noun (an unerring shot), not after a verb — you would not normally say "his aim was unerring" in speech, though a writer might. Second, the noun it goes with is usually the ability itself (aim, eye, instinct, accuracy, judgement, sense), not the person. And honestly, people use it a little loosely: a player described as having unerring accuracy still misses sometimes. The word means "so reliable it feels like it never fails", and that is how listeners take it.

百發百中的、從不失誤的（多用來形容準頭、直覺、判斷力）