a marksman with a pistol or rifle.
a gunfighter, as in the Old West.

Origin of shootist

An Americanism dating back to 1860–65; shoot1 + -ist Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for shootist

Historical Examples of shootist

Word Origin and History for shootist

1864, from shoot (v.) + -ist.

Online Etymology Dictionary, © 2010 Douglas Harper