cusp

n pointed end where two curves meet （两弧线相交所形成的）尖端: the cusp of a crescent/a leaf 月牙[叶子]的尖端.

cursorily, cursory, curt, curtail, curtailed, curtailment, curtain, curtain-call, curtain-raiser, curtly, curtness, curtsey (also curtsy), curvaceous, curvature, curve, curved, curved glass, curvy, cushion, cushy, cuss, cussed, custard, custard pie, custodial, custodian, custody, custom, Custom House, custom-built (also custom-made), customarily, customary, customer, customize, customize, -ise, customs, customs house, customs union, cut, cut across,