also: いっかごと
noun
one's own opinion; personal view
Refers to a strongly held personal opinion or theory, often in a specialized field. Implies the speaker has some authority or confidence in their view.
彼は教育問題について一家言を持っている。
He has his own strong opinions on educational issues.
この分野では、彼女
In this field, she is an expert with her own well-defined views.