Boring is a method of machining on a prefabricated hole with a cutting tool to make it enlarged, and the boring work can be carried out either on a boring machine or on a lathe.

​镗孔，指的是对锻出，铸出或钻出孔的进一步加工。镗孔可扩大孔径，提高精度，减小表面粗糙度，还可以较好地纠正原来孔轴线的偏斜。镗孔可以分为粗镗、半精镗和精镗。