propaedeutic vs preceding

propaedeutic is a noun but preceding is not a noun.

Word	Noun	Adjective	Verb	Adverb
propaedeutic	Yes	Yes	No	No
preceding	No	Yes	No	No

propaedeutic (noun)	preceding (noun)
a course that provides an introduction to an art or science (or to more advanced study generally)

propaedeutic (adjective)	preceding (adjective)
preceding and preparing for something	existing or coming before
	of a person who has held and relinquished a position or office