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.
The gasman is a man who works for a gas company, repairing gas appliances in people's houses, or checking how much gas they have used. gasmen someone whose job is to come to your home to see how much gas you have used or to repair your gas system
{i} person who works in a gas company; worker who checks gas meters and marks the amount of gas used in a specific period; person who produces and sells or distributes gas for commercial or industrial use; (Mining) person who checks a mine for the presence of poisonous gases and other hazards