Tra"cer (?), n.
One who, or that which, traces.
© Webster 1913
Trac"er (?), n.
1.
A person engaged (esp. in the express or railway service) in tracing, or searching out, missing articles, as packages or freight cars.
2.
An inquiry sent out (esp. in transportation service) for a missing article, as a letter or an express package.
© Webster 1913