i Register
In some senses, monologize is marked as rare. Watch for register when choosing this word.
verb
To deliver a monologue.
"No, Mr. Blenkinsop," he replied to the submissive curate, standing on his hearth-rug at full height and regarding the cornice as his habit was when he began to monologize—"no, I find it impossible to entertain such an accusation."
To deliver in the form of a monologue.