2ADJ-GRADED [usually ADJ n](目光)敏锐的,锐利的 If someone has piercing eyes or a piercing stare, they seem to look at you very intensely. (目光)敏锐的,锐利的 [written]
3ADJ-GRADED [ADJ n](感情等)深切的,直入肺腑的 If you describe a quality or feeling as piercing, you mean that it makes you experience a feeling, especially sadness, very strongly. (感情等)深切的,直入肺腑的 [literary]
She was aware of a sharp piercing regret.
她感到一种深彻入骨的悔恨。
4ADJ-GRADED (风)刺骨的,凛冽的 A piercing wind makes you feel very cold. (风)刺骨的,凛冽的