數學上，函數的k階切點，或稱觸點，接點（point of contact, tangent point）是一個等價關係，表示函數在點P有同樣的取值並且有直到k階的相同的導數。等價類通常稱為射流。
曲線和幾何對象也可以有k階切點，這也稱為密切(也就是吻合)，它是相切的性質的推廣。例如：密切圓。
參見
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