i Register
In some senses, short-timer is marked as slang, US, historical, colloquial. Watch for register when choosing this word.
noun
A soldier during the Vietnam War who had less than two months to serve.
Almost every Marine in Viet Nam carries a short-timer’s calendar of his tour of duty—the usual 365 days—plus a bonus of 20 days for being a Marine.
A person who would not be required to do a difficult or dangerous task.
An employee who has given notice of their intent to leave.
The customer of a prostitute.