discourse vs dissertate

discourse is a noun but dissertate is not a noun.

Word	Noun	Adjective	Verb	Adverb
discourse	Yes	No	Yes	No
dissertate	No	No	Yes	No

As verbs, discourse and dissertate are synonyms defined as:

Other synonyms of discourse include hold forth.

discourse (noun)	dissertate (noun)
an extended communication (often interactive) dealing with some particular topic
extended verbal expression in speech or writing
an address of a religious nature (usually delivered during a church service)

discourse (verb)	dissertate (verb)
talk at length and formally about a topic	talk at length and formally about a topic
carry on a conversation
to consider or examine in speech or writing