We don't have synonyms for gasman yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are gagman, masman and tasman.
°(colloquial) A worker for a company that supplies gas (in the sense of the gaseous fuel), especially one who visits premises to read the meter, test appliances etc.
"I spent all morning waiting for the gasman to call."
°(colloquial) A worker for a company that supplies gas (in the sense of the gaseous fuel), especially one who visits premises to read the meter, test appliances etc.
"I spent all morning waiting for the gasman to call."