his opinion; her opinion; that person's opinion
Refers to the opinion of a specific person previously mentioned or understood from context. 氏 is a formal or written way to say 'he' or 'that person', often used in news or academic writing.
His opinion had a great influence at the meeting.
I would like to hear his opinion on this matter.
Compound of 氏 (し, 'he' or 'that person', a formal pronoun) + の (possessive particle) + 意見 (いけん, 'opinion'). The word is transparently derived from its components.