1) Discourse 2) Discourse at length 3) Speak 4) Talk 
• (v. i.) To deal in dissertation; to write dissertations; to discourse.
Dis'ser·tate intransitive verb [ Latin dissertatus , past participle of dissertare to discuss, intents, from disserere . See Dissert .] To deal in dissertation; to write dissertations; to discourse. [ R.] J. Foster. 
dissertate 1. To formally discourse or to present a formal viewpoint. 2. To discuss a subject fully and learnedly; to discourse.
to discuss a subject fully and learnedly; discourse.