Colloquial term for an engineer or technician, often with a nuance of a hands-on, practical person rather than an academic researcher. Compare with 技術者, which is more formal and neutral.
See also: 技術者
He's not just a technician; he keeps coming up with new ideas.
Our company has many excellent engineers.
Compound of 技術 (gijutsu, 'technology') and 屋 (ya, suffix for a person engaged in a trade or profession). The 屋 suffix often adds a colloquial or shop-like nuance.