technical advisor; expert advisor
A person who provides specialized technical advice, often in a corporate or project setting.
We hired a technical advisor for the new project.
He is active as a technical advisor for a major company.
顧問 is a general advisor or counselor, while 技術顧問 specifies a technical or engineering advisory role.
コンサルタント is a broader term for consultant, often used in business contexts, whereas 技術顧問 emphasizes technical expertise.
Compound of 技術 (technology, technique) and 顧問 (advisor, counselor).