Airborne solid particulate matter generated by the welding or cutting process. Fume particles are usually sub-micron in size and thus tend to remain airborne and drift with the air currents.

Related Links

Fumes | Definition of Fumes at Dictionary.com
Fume | Definition of Fume
FUMES | definition in the Cambridge English Dictionary
fumes (noun) American English definition and synonyms | Macmillan Dictionary
fume – Wiktionary