Fully versed about is a phrase that means to have a thorough understanding of a subject. It is often used to describe someone who has a great deal of knowledge and experience in a particular area. The crossword solutions for the term fully versed about are UPON and INON. UPON is a preposition that means 'on top of' or 'OVER'. INON is an adverb that means 'in a certain way' or 'in a particular manner'. Together, these two words suggest that someone is knowledgeable and experienced in a particular subject.