Answer
$HCl$ is hydrochloric acid.
Work Step by Step
Binary acids, or acids formed from 2 elements are named by writing "hydro," followed by the root name of the second element, followed by "-ic" and the word "acid".
$Cl$ is chloride, so the root used in the name of the acid is "chlor."
The name is thus formed as hydro+chlor+ic acid.
$HCl$ is hydrochloric acid.
