Definition:P-adic Unit

Definition
Let $p$ be a prime number.

Let $\struct {\Q_p, \norm {\,\cdot\,}_p}$ be the $p$-adic numbers.

Let $\Z_p$ denote the $p$-adic integers.

The set of $p$-adic units, denoted $\Z_p^\times$, is the set of invertible elements of $\Z_p$.

From Leigh.Samphier/Sandbox/P-adic Units is Set with Norm Equal to One, the set of $p$-adic units is:
 * $\Z_p^\times = \set {x \in \Q_p: \norm x_p = 1}$