tightwad; miser; penny-pincher
Colloquial term for a stingy person who is overly careful with money. Often used in casual conversation.
He's such a tightwad he won't even treat his friends to a coffee.
That miserly company president rarely raises his employees' salaries.
Compound of the mimetic adverb がっちり (firmly, tightly) and 屋 (person with a certain trait). The exact origin of がっちり is uncertain, but it likely derives from sound symbolism suggesting tightness or solidity.