1. to write or publish an editorial; to express an opinion in the manner of an editorial
Usage: British spelling; American English uses 'editorialize'
2. to insert editorial comments or opinions into a text, report, or account that should be factual or neutral
Usage: often used critically to describe inappropriate injection of bias

Examples

• The newspaper columnist tends to editorialise rather than simply report the news.
• She was asked to write a summary, but she editorialised throughout the document.
• The broadcaster editorialised about the election results during the evening broadcast.
• Journalists should inform the public without editorialising their personal views.
• He editorialised in his review, making it clear he disliked the film.
• The report editorialised too much instead of sticking to the facts.