Refers to a manual or blue-collar worker. The term can carry a somewhat dated or class-conscious nuance and is marked as sensitive, so it may be perceived as condescending or old-fashioned in modern contexts.
When he was young, he worked as a laborer at the port.
Compound of 労務 (rōmu, 'labor') + 者 (sha, 'person'). The exact historical derivation is uncertain, but the term has been used since the early 20th century to refer to manual laborers.