高超音速（hypersonic，亦称极音速），空气动力学名词，意指速度较超音速还高出许多的状态。在1970年代，这个词通常指的是5马赫（5倍音速）或更高的速度。高超音速流态（hypersonic regime）是超音速流态的分支。

超音速气流与亚音速气流性质迥异。当一飞行器加速到超音速，路径中几乎所有的空气特性剧烈地改变。不过尽管有如此明显的界线，对于「超音速」的定义仍有一些争议。其中一个定义是整架飞行器各部份速度皆在1马赫或之上。更技术性地定义指出：整架飞行器周遭的所有气流速度皆是超音速才能称作是超音速，这样的情形对寻常设计的飞行器来说，通常是出现在1.2马赫上下。0.8到1.2马赫的范围因此称作跨音速。

In aerodynamics, a hypersonic speed is one that is highly supersonic. Since the 1970s, the term has generally been assumed to refer to speeds of Mach 5 and above.

The precise Mach number at which a craft can be said to be flying at hypersonic speed varies, since individual physical changes in the airflow (like molecular dissociation and ionization) occur at different speeds; these effects collectively become important around Mach 5. The hypersonic regime is often alternatively defined as speeds where ramjets do not produce net thrust.